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path: root/drivers/usb/host/ehci-sched.c
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2013-10-19USB: EHCI: fix sparse errorsAlan Stern
This patch fixes several sparse errors in ehci-hcd introduced by commit 3d091a6f7039 (USB: EHCI: AMD periodic frame list table quirk). Although the problem fixed by that commit affects only little-endian systems, the source code has to use types appropriate for big-endian too. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-19USB: EHCI: fix type mismatch in check_intr_scheduleAlan Stern
This patch fixes a type mismatch in ehci-hcd caused by commit b35c5009bbf6 (USB: EHCI: create per-TT bandwidth tables). The c_maskp parameter in check_intr_schedule() was changed to point to unsigned int rather than __hc32, but the prototype declaration wasn't adjusted accordingly. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-14USB: EHCI: start new isochronous streams ASAPAlan Stern
This patch changes the initial delay before the startup of a newly scheduled isochronous stream. Currently the stream doesn't start for at least 5 ms (40 microframes). This value is just an estimate; it has no real justification. Instead, we can start the stream as soon as possible after the scheduling computations are complete. Essentially this requires nothing more than reading the frame counter after the stream is scheduled, instead of before. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-14USB: EHCI: create per-TT bandwidth tablesAlan Stern
This patch continues the scheduling changes in ehci-hcd by adding a table to store the bandwidth allocation below each TT. This will speed up the scheduling code, as it will no longer need to read through the entire schedule to compute the bandwidth currently in use. Properly speaking, the FS/LS budget calculations should be done in terms of full-speed bytes per microframe, as described in the USB-2 spec. However the driver currently uses microseconds per microframe, and the scheduling code isn't robust enough at this point to change over. For the time being, we leave the calculations as they are. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-11USB: EHCI: use a bandwidth-allocation tableAlan Stern
This patch significantly changes the scheduling code in ehci-hcd. Instead of calculating the current bandwidth utilization by trudging through the schedule and adding up the times used by the existing transfers, we will now maintain a table holding the time used for each of 64 microframes. This will drastically speed up the bandwidth computations. In addition, it eliminates a theoretical bug. An isochronous endpoint may have bandwidth reserved even at times when it has no transfers listed in the schedule. The table will keep track of the reserved bandwidth, whereas adding up entries in the schedule would miss it. As a corollary, we can keep bandwidth reserved for endpoints even when they aren't in active use. Eventually the bandwidth will be reserved when a new alternate setting is installed; for now the endpoint's reservation takes place when its first URB is submitted. A drawback of this approach is that transfers with an interval larger than 64 microframes will have to be charged for bandwidth as though the interval was 64. In practice this shouldn't matter much; transfers with longer intervals tend to be rather short anyway (things like hubs or HID devices). Another minor drawback is that we will keep track of two different period and phase values: the actual ones and the ones used for bandwidth allocation (which are limited to 64). This adds only a small amount of overhead: 3 bytes for each endpoint. The patch also adds a new debugfs file named "bandwidth" to display the information stored in the new table. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-11USB: EHCI: create a "periodic schedule info" structAlan Stern
This patch begins the process of unifying the scheduling parameters that ehci-hcd uses for interrupt and isochronous transfers. It creates an ehci_per_sched structure, which will be stored in both ehci_qh and ehci_iso_stream structures, and will contain the common scheduling information needed for both. Initially we merely create the new structure and move some existing fields into it. Later patches will add more fields and utilize these structures in improved scheduling algorithms. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-11USB: EHCI: use consistent NO_FRAME valueAlan Stern
ehci-hcd is inconsistent in the sentinel values it uses to indicate that no frame number has been assigned for a periodic transfer. Some places it uses NO_FRAME (defined as 65535), other places it uses -1, and elsewhere it uses 9999. This patch defines a value for NO_FRAME which can fit in a 16-bit signed integer, and changes the code to use it everywhere. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-11USB: EHCI: No SSPLIT allowed in uframe 7Alan Stern
The scheduling code in ehci-hcd contains an error. For full-speed isochronous-OUT transfers, the EHCI spec forbids scheduling Start-Split transactions in H-microframe 7, but the driver allows it anyway. This patch adds a check to prevent it. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-11USB: EHCI: compute full-speed bandwidth usage correctlyAlan Stern
Although the bandwidth statistics maintained by ehci-hcd show up only in the /sys/kernel/debug/usb/devices file, they ought to be calculated correctly. The calculation for full-speed isochronous endpoints is wrong; it mistakenly yields bytes per microframe instead of bytes per frame. The "interval" value, which is in frames, should not be converted to microframes. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-11USB: EHCI: check the right uframes for CSPLITAlan Stern
The check_intr_schedule() routine in ehci-hcd looks at the wrong microframes when checking to see if a full-speed or low-speed interrupt endpoint will fit in the periodic schedule. If the Start-Split transaction is scheduled for microframe N then the Complete-Split transactions get scheduled for microframes N+2, N+3, and N+4. However the code considers N+1, N+2, and N+3 instead. This patch fixes the limits on the "for" loop and also improves the use of whitespace. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-17USB: EHCI: handle isochronous underruns with taskletsAlan Stern
This patch updates the iso_stream_schedule() routine in ehci-sched.c to handle cases where an underrun causes an isochronous endpoint's queue to empty out, but the client driver wants to maintain synchronization with the device (i.e., the URB_ISO_ASAP flag is not set). This could not happen until recently, when ehci-hcd switched over to completing URBs in a tasklet. (This may seem like an unlikely case to worry about, but underruns are all too common with the snd-usb-audio driver, which doesn't use URB_ISO_ASAP.) As part of the fix, some URBs may need to be given back when they are submitted. This is necessary when the URB's scheduled slots all fall before the current value of ehci->last_iso_frame, and as an optimization we do it also when the slots all fall before the current frame number. As a second part of the fix, we may need to skip some but not all of an URB's packets. This is necessary when some of the URB's scheduled slots fall before the current value of ehci->last_iso_frame and some of them fall after the current frame number. A new field (first_packet) is added to struct ehci_iso_sched, to indicate how many packets should be skipped. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-17USB: EHCI: code rearrangement in iso_stream_schedule()Alan Stern
This patch interchanges the "if" and "else" branches of the big "if" statement in iso_stream_schedule(), in preparation for the next patch in this series. That is, it changes if (likely(!...)) { A } else { B } to if (unlikely(...)) { B } else { A } Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-30ehci: enable debugging code when CONFIG_DYNAMIC_DEBUG is setXenia Ragiadakou
The debugging code for ehci is enabled to run if the DEBUG flag is defined. This patch enables the debugging code also when the kernel is configured with dynamic debugging on. Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-30ehci: remove ehci_vdbg() verbose debugging statementsXenia Ragiadakou
This patch removes ehci_vdbg debugging statements from EHCI host controller driver because they produce too much information, lowering the signal to noise ratio when debugging, and because they are not used anymore. Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-18Merge 3.11-rc6 into usb-nextGreg Kroah-Hartman
We want these USB fixes in this branch as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-12USB: EHCI: accept very late isochronous URBsAlan Stern
Since commits 4005ad4390bf (EHCI: implement new semantics for URB_ISO_ASAP) and c75c5ab575af (ALSA: USB: adjust for changed 3.8 USB API) became widely distributed, people have been experiencing problems with audio transfers. The slightest underrun causes complete failure, requiring the audio stream to be restarted. It turns out that the current isochronous API doesn't handle underruns in the best way. The ALSA developers would much rather have transfers that are submitted too late be accepted and complete in the normal fashion, rather than being refused outright. This patch implements the requested approach. When an isochronous URB submission is so late that all its scheduled slots have already expired, a debugging message will be printed in the log and the URB will be accepted as usual. Assuming it was submitted by a completion handler (which is normally the case), it will complete shortly thereafter with all the usb_iso_packet_descriptor status fields marked -EXDEV. This fixes (for ehci-hcd) https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1191603 It should be applied to all kernels that include commit 4005ad4390bf. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Tested-by: Maksim Boyko <maksboyko@yandex.ru> CC: Clemens Ladisch <clemens@ladisch.de> CC: <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-12USB: EHCI: improve interrupt qh unlinkMing Lei
ehci-hcd currently unlinks an interrupt QH when it becomes empty, that is, after its last URB completes. This works well because in almost all cases, the completion handler for an interrupt URB resubmits the URB; therefore the QH doesn't become empty and doesn't get unlinked. When we start using tasklets for URB completion, this scheme won't work as well. The resubmission won't occur until the tasklet runs, which will be some time after the completion is queued with the tasklet. During that delay, the QH will be empty and so will be unlinked unnecessarily. To prevent this problem, this patch adds a 5-ms time delay before empty interrupt QHs are unlinked. Most often, during that time the interrupt URB will be resubmitted and thus we can avoid unlinking the QH. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-05-30USB: EHCI: fix regression related to qh_refresh()Alan Stern
This patch adds some code that inadvertently got left out of commit c1fdb68e3d73741630ca16695cf9176c233be7ed (USB: EHCI: changes related to qh_refresh()). The calls to qh_refresh() and qh_link_periodic() were taken out of qh_schedule(); therefore it is necessary to call these routines manually after calling qh_schedule(). Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Reported-and-tested-by: Oleksij Rempel <linux@rempel-privat.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-05-29USB: revert periodic scheduling bugfixAlan Stern
This patch reverts commit 3e619d04159be54b3daa0b7036b0ce9e067f4b5d (USB: EHCI: fix bug in scheduling periodic split transfers). The commit was valid -- it fixed a real bug -- but the periodic scheduler in ehci-hcd is in such bad shape (especially the part that handles split transactions) that fixing one bug is very likely to cause another to surface. That's what happened in this case; the result was choppy and noisy playback on certain 24-bit audio devices. The only real fix will be to rewrite this entire section of code. My next project... This fixes https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1136110. Thanks to Tim Richardson for extra testing and feedback, and to Joseph Salisbury and Tyson Tan for tracking down the original source of the problem. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: Joseph Salisbury <joseph.salisbury@canonical.com> CC: Tim Richardson <tim@tim-richardson.net> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-28Merge branch 'usb-linus' into usb-nextGreg Kroah-Hartman
This lets us fix the build error that happens when these two trees are merged together. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25USB: EHCI: fix bug in iTD/siTD DMA pool allocationSoeren Moch
[Description written by Alan Stern] Soeren tracked down a very difficult bug in ehci-hcd's DMA pool management of iTD and siTD structures. Some background: ehci-hcd gives each isochronous endpoint its own set of active and free itd's (or sitd's for full-speed devices). When a new itd is needed, it is taken from the head of the free list, if possible. However, itd's must not be used twice in a single frame because the hardware continues to access the data structure for the entire duration of a frame. Therefore if the itd at the head of the free list has its "frame" member equal to the current value of ehci->now_frame, it cannot be reused and instead a new itd is allocated from the DMA pool. The entries on the free list are not released back to the pool until the endpoint is no longer in use. The bug arises from the fact that sometimes an itd can be moved back onto the free list before itd->frame has been set properly. In Soeren's case, this happened because ehci-hcd can allocate one more itd than it actually needs for an URB; the extra itd may or may not be required depending on how the transfer aligns with a frame boundary. For example, an URB with 8 isochronous packets will cause two itd's to be allocated. If the URB is scheduled to start in microframe 3 of frame N then it will require both itds: one for microframes 3 - 7 of frame N and one for microframes 0 - 2 of frame N+1. But if the URB had been scheduled to start in microframe 0 then it would require only the first itd, which could cover microframes 0 - 7 of frame N. The second itd would be returned to the end of the free list. The itd allocation routine initializes the entire structure to 0, so the extra itd ends up on the free list with itd->frame set to 0 instead of a meaningful value. After a while the itd reaches the head of the list, and occasionally this happens when ehci->now_frame is equal to 0. Then, even though it would be okay to reuse this itd, the driver thinks it must get another itd from the DMA pool. For as long as the isochronous endpoint remains in use, this flaw in the mechanism causes more and more itd's to be taken slowly from the DMA pool. Since none are released back, the pool eventually becomes exhausted. This reuslts in memory allocation failures, which typically show up during a long-running audio stream. Video might suffer the same effect. The fix is very simple. To prevent allocations from the pool when they aren't needed, make sure that itd's sent back to the free list prematurely have itd->frame set to an invalid value which can never be equal to ehci->now_frame. This should be applied to -stable kernels going back to 3.6. Signed-off-by: Soeren Moch <smoch@web.de> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25USB: EHCI: convert singly-linked lists to list_headsAlan Stern
This patch (as1664) converts ehci-hcd's async_unlink, async_iaa, and intr_unlink from singly-linked lists to standard doubly-linked list_heads. Originally it didn't seem necessary to use list_heads, because items are always added to and removed from these lists in FIFO order. But now with more list processing going on, it's easier to use the standard routines than continue with a roll-your-own approach. I don't know if the code ends up being notably shorter, but the patterns will be more familiar to any kernel hacker. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25USB: EHCI: split needs_rescan into two flagsAlan Stern
This patch (as1662) does some more QH-related cleanup in ehci-hcd. The qh->needs_rescan flag is currently used for two different purposes; the patch replaces it with two separate flags for greater clarity: qh->dequeue_during_giveback indicates that a completion handler dequeued an URB (implying that a rescan is needed), and qh->exception indicates that the QH is in an exceptional state requiring an unlink (either it encountered an I/O error or an unlink was requested). The new flags get set where the dequeue, exception, or unlink request occurred, rather than where the unlink is started. This is so that in the future, if we need to, we will be able to tell apart unlinks that truly were required from those that were carried out merely because the QH wasn't being used. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25USB: EHCI: change return value of qh_completions()Alan Stern
This patch (as1658) cleans up the usage of qh_completions() in ehci-hcd. Currently the function's return value indicates whether any URBs were given back; the idea was that the caller can scan the QH over again to handle any URBs that were dequeued by a completion handler. This is not necessary; when qh_completions() is ready to give back dequeued URBs, it does its own rescanning. Therefore the new return value will be a flag indicating whether the caller needs to unlink the QH. This is more convenient than forcing the caller to check qh->needs_rescan, and it makes a lot more sense -- why should "needs_rescan" imply that an unlink is needed? The callers are also changed to remove the unneeded rescans. Lastly, the check for whether qh->qtd_list is non-empty is removed from the start of qh_completions(). Two of the callers have to make this test anyway, so the same test can simply be added to the other two callers. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25USB: EHCI: changes related to qh_refresh()Alan Stern
This patch (as1638) makes several changes to the ehci-hcd driver, all related to the qh_refresh() function. This function must be called whenever an idle QH gets linked back into either the async or the periodic schedule. Change a BUG_ON() in the qh_update routine to a WARN_ON(). Since this code runs in atomic context, a BUG_ON() would immediately freeze the whole system. Remove two unneeded calls to qh_refresh(), one when a QH is initialized and one when a QH becomes idle. Adjust the adjacent comments accordingly. Move the qh_refresh() and qh_link_periodic() calls for new interrupt URBs to after the new TDs have been added. As a result of the previous two changes, qh_refresh() is never called when the qtd_list is empty. The corresponding check in qh_refresh() can be removed, along with an indentation level. These changes should not cause any alteration of behavior. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-31USB: EHCI: fix bug in scheduling periodic split transfersAlan Stern
This patch (as1654) fixes a very old bug in ehci-hcd, connected with scheduling of periodic split transfers. The calculations for full/low-speed bus usage are all carried out after the correction for bit-stuffing has been applied, but the values in the max_tt_usecs array assume it hasn't been. The array should allow for allocation of up to 90% of the bus capacity, which is 900 us, not 780 us. The symptom caused by this bug is that any isochronous transfer to a full-speed device with a maxpacket size larger than about 980 bytes is always rejected with a -ENOSPC error. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-31USB: EHCI: fix for leaking isochronous dataAlan Stern
This patch (as1653) fixes a bug in ehci-hcd. Unlike iTD entries, an siTD entry in the periodic schedule may not complete until the frame after the one it belongs to. Consequently, when scanning the periodic schedule it is necessary to start with the frame _preceding_ the one where the previous scan ended. Not doing this properly can result in memory leaks and failures to complete isochronous URBs. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Reported-by: Andy Leiserson <andy@leiserson.org> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-11-11USB: EHCI: bugfix: urb->hcpriv should not be NULLAlan Stern
This patch (as1632b) fixes a bug in ehci-hcd. The USB core uses urb->hcpriv to determine whether or not an URB is active; host controller drivers are supposed to set this pointer to a non-NULL value when an URB is queued. However ehci-hcd sets it to NULL for isochronous URBs, which defeats the check in usbcore. In itself this isn't a big deal. But people have recently found that certain sequences of actions will cause the snd-usb-audio driver to reuse URBs without waiting for them to complete. In the absence of proper checking by usbcore, the URBs get added to their endpoint list twice. This leads to list corruption and a system freeze. The patch makes ehci-hcd assign a meaningful value to urb->hcpriv for isochronous URBs. Improving robustness always helps. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Reported-by: Artem S. Tashkinov <t.artem@lycos.com> Reported-by: Christof Meerwald <cmeerw@cmeerw.org> CC: <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-24USB: EHCI: make ehci_read_frame_index platform independentAlan Stern
In preparation for splitting the ehci-hcd driver into a core library and separate platform-specific driver modules, this patch (as1617) changes the way ehci_read_frame_index() is handled. Since the same core library will have to work with both PCI and non-PCI platforms, the quirk handler routine will be compiled unconditionally. The decision about whether to call it or simply to read the frame index register is made at run time, based on whether the frame_index_bug quirk flag is set. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22EHCI: implement new semantics for URB_ISO_ASAPAlan Stern
This patch (as1612) updates the isochronous scheduling and processing in ehci-hcd to match the new semantics for URB_ISO_ASAP. It also adds a missing "unlikely" in sitd_complete() to match the corresponding statement in itd_complete(), and it increments urb->error_count in a couple of places that had been overlooked. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22EHCI: replace mult/div with bit-mask operationAlan Stern
This patch (as1610) replaces multiplication and divison operations in ehci-hcd's isochronous scheduling code with a bit-mask operation, taking advantage of the fact that isochronous periods are always powers of 2. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22EHCI: use the isochronous scheduling thresholdAlan Stern
This patch (as1609) changes the way ehci-hcd uses the "Isochronous Scheduling Threshold" in its calculations. Until now the code has ignored the threshold except for certain Intel PCI-based controllers. This violates the EHCI spec. The new code takes the threshold into account always, removing the need for the fs_i_thresh quirk flag. In addition it implements the "full frame cache" setting more efficiently, moving forward only as far as the next frame boundary instead of always moving forward 8 microframes. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22EHCI: improved logic for isochronous schedulingAlan Stern
This patch (as1608) reworks the logic used by ehci-hcd for scheduling isochronous transfers. Now the modular calculations are all based on a window that starts at the last frame scanned for isochronous completions. No transfer descriptors for any earlier frames can possibly remain on the schedule, so there can be no confusion from schedule wrap-around. This removes the need for a "slop" region of arbitrary size. There's no need to check for URBs that are longer than the schedule length. With the old code they could throw things off by wrapping around and appearing to end in the near future rather than the distant future. Now such confusion isn't possible, and the existing test for submissions that extend too far into the future will also catch those that exceed the schedule length. (But there still has to be an initial test to handle the case where the schedule already extends as far into the future as possible.) Delays caused by IRQ latency won't confuse the algorithm unless they are ridiculously long (over 250 ms); they will merely reduce how far into the future new transfers can be scheduled. A few people have reported problems caused by delays of 50 ms or so. Now instead of failing completely, isochronous transfers will experience a brief glitch and then continue normally. (Whether this is truly a good thing is debatable. A latency as large as 50 ms generally indicates a bug is present, and complete failure of audio or video transfers draws people's attention pretty vividly. Making the transfers more robust also makes it easier for such bugs to remain undetected.) Finally, ehci->next_frame is renamed to ehci->last_iso_frame, because that better describes what it is: the last frame to have been scanned for isochronous completions. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16USB: EHCI: simplify isochronous scanningAlan Stern
This patch (as1587) simplifies ehci-hcd's scan_isoc() routine by eliminating some local variables, declaring boolean-valued values as bool rather than unsigned, changing variable names to make more sense, and so on. The logic at the end of the routine is cut down significantly. The scanning doesn't have to catch up all the way to where the hardware is; it merely has to catch up to where the hardware was when the last interrupt occurred. If the hardware has made more progress since then and issued another interrupt, a rescan will catch up to it. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16USB: EHCI: use hrtimer for the I/O watchdogAlan Stern
This patch (as1586) replaces the kernel timer used by ehci-hcd as an I/O watchdog with an hrtimer event. Unlike in the current code, the watchdog event is now always enabled whenever any isochronous URBs are active. This will prevent bugs caused by the periodic schedule wrapping around with no completion interrupts; the watchdog handler is guaranteed to scan the isochronous transfers at least once during each iteration of the schedule. The extra overhead will be negligible: one timer interrupt every 100 ms. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16USB: EHCI: always scan each interrupt QHAlan Stern
This patch (as1585) fixes a bug in ehci-hcd's scheme for scanning interrupt QHs. Currently a single routine takes care of scanning everything on the periodic schedule. Whenever an interrupt occurs, it scans all isochronous and interrupt URBs scheduled for frames that have elapsed since the last scan. This has two disadvantages. The first is relatively minor: An interrupt QH is likely to end up getting scanned multiple times, particularly if the last scan was not fairly recent. (The current code avoids this by maintaining a periodic_stamp in each interrupt QH.) The second is more serious. The periodic schedule wraps around. If the last scan occurred during frame N, and the next scan occurs when the schedule has gone through an entire cycle and is back at frame N, the scanning code won't look at any frames other than N. Consequently it won't see any QHs that completed during frame N-1 or earlier. The patch replaces the entire frame-based approach for scanning interrupt QHs with a new routine using a list-based approach, the same as for async QHs. This has a slight disadvantage, because it means that all interrupt QHs have to be scanned every time. But it is more robust than the current approach. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16USB: EHCI: don't refcount iso_stream structuresAlan Stern
This patch (as1580) makes ehci_iso_stream structures behave more like QHs, in that they will remain allocated until their isochronous endpoint is disabled. This will come in useful in the future, when periodic bandwidth gets allocated as an altsetting is installed rather than on-the-fly. For now, the change to the ehci_iso_stream lifetimes means that each structure is always deallocated at exactly one spot in ehci_endpoint_disable() and never used again. As a result, it is no longer necessary to use reference counting on these things, and the patch removes it. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16USB: EHCI: use hrtimer for (s)iTD deallocationAlan Stern
This patch (as1579) adds an hrtimer event to handle deallocation of iTDs and siTDs in ehci-hcd. Because of the frame-oriented approach used by the EHCI periodic schedule, the hardware can continue to access the Transfer Descriptor for isochronous (or split-isochronous) transactions for up to a millisecond after the transaction completes. The iTD (or siTD) must not be reused before then. The strategy currently used involves putting completed iTDs on a list of cached entries and every so often returning them to the endpoint's free list. The new strategy reduces overhead by putting completed iTDs back on the free list immediately, although they are not reused until it is safe to do so. When the isochronous endpoint stops (its queue becomes empty), the iTDs on its free list get moved to a global list, from which they will be deallocated after a minimum of 2 ms. This delay is what the new hrtimer event is for. Overall this may not be a tremendous improvement over the current code, but to me it seems a lot more clear and logical. In addition, it removes the need for each iTD to keep a reference to the ehci_iso_stream it belongs to, since the iTD never needs to be moved back to the stream's free list from the global list. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16USB: EHCI: use hrtimer for interrupt QH unlinkAlan Stern
This patch (as1577) adds hrtimer support for unlinking interrupt QHs in ehci-hcd. The current code relies on a fixed delay of either 2 or 55 us, which is not always adequate and in any case is totally bogus. Thanks to internal caching, the EHCI hardware may continue to access an interrupt QH for more than a millisecond after it has been unlinked. In fact, the EHCI spec doesn't say how long to wait before using an unlinked interrupt QH. The patch sets the delay to 9 microframes minimum, which ought to be adequate. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16USB: EHCI: return void instead of 0Alan Stern
This patch (as1574) changes the return type of multiple functions in ehci-sched.c from int to void. The values they return are now always 0, so there's no reason for them to return any value at all. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16USB: EHCI: use hrtimer for the periodic scheduleAlan Stern
This patch (as1573) adds hrtimer support for managing ehci-hcd's periodic schedule. There are two issues to deal with. First, the schedule's state (on or off) must not be changed until the hardware status has caught up with the current command. This is handled by an hrtimer event that polls at 1-ms intervals to see when the Periodic Schedule Status (PSS) flag matches the Periodic Schedule Enable (PSE) value. Second, the schedule should not be turned off as soon as it becomes empty. Turning the schedule on and off takes time, so we want to wait until the schedule has been empty for a suitable period before turning it off. This is handled by an hrtimer event that gets set to expire 10 ms after the periodic schedule becomes empty. The existing code polls (for up to 1125 us and with interrupts disabled!) to check the status, and doesn't implement a delay before turning off the schedule. Furthermore, if the polling fails then the driver decides that the controller has died. This has caused problems for several people; some controllers can take 10 ms or more to turn off their periodic schedules. This patch fixes these issues. It also makes the "broken_periodic" workaround unnecessary; there is no longer any danger of turning off the periodic schedule after it has been on for less than 1 ms. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16USB: EHCI: add new root-hub state: STOPPINGAlan Stern
This patch (as1571) adds a new state for ehci-hcd's root hubs: EHCI_RH_STOPPING. This value is used at times when the root hub is being stopped and we don't know whether or not the hardware has finished all its DMA yet. Although the purpose may not be apparent, this distinction will come in useful later on. Future patches will avoid actions that depend on the root hub being operational (like turning on the async or periodic schedules) when they see the state is EHCI_RH_STOPPING. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16USB: EHCI: don't refcount QHsAlan Stern
This patch (as1567) removes ehci-hcd's reference counting of QH structures. It's not necessary to refcount these things because they always get deallocated at exactly one spot in ehci_endpoint_disable() (except for two special QHs, ehci->async and ehci->dummy) and are never used again. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-14USB: EHCI: improve full-speed isochronous scheduling routineAlan Stern
This patch (as1555) improves the code ehci-hcd uses while checking the periodic schedule for isochronous transfers to full-speed devices. In addition to making sure that a new transfer does not violate the restrictions on the high-speed schedule, it also has to check the restrictions on the full-speed part of the bus, i.e., the part beyond the Transaction Translator (TT). It does this by calling tt_available() (or tt_no_collision() if CONFIG_USB_EHCI_TT_NEWSCHED isn't enabled). However it calls that routine on each pass through a loop over the frames being modified, which is an unnecessary expense because tt_available() (or tt_no_collision) already does its own loop over frames. It is sufficient to do the check just once, before starting the loop. In addition, the function calls incorrectly converted the transfer's period from microframes to frames by doing a left shift instead of a right shift. The patch fixes this while moving the calls. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-01USB: ehci-sched.c: remove dbg() usageGreg Kroah-Hartman
dbg() was a very old USB-specific macro that should no longer be used. This patch removes it from being used in the driver and uses dev_dbg() instead. CC: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-23EHCI: maintain the ehci->command value properlyAlan Stern
The ehci-hcd driver is a little haphazard about keeping track of the state of the USBCMD register. The ehci->command field is supposed to hold the register's value (apart from a few special bits) at all times, but it isn't maintained properly. This patch (as1543) cleans up the situation. It keeps ehci->command up-to-date, and uses that value rather than reading the register from the hardware whenever possible. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2011-11-29EHCI : Fix a regression in the ISO schedulerMatthieu CASTET
Fix a regression that was introduced by commit 811c926c538f7e8d3c08b630dd5844efd7e000f6 (USB: EHCI: fix HUB TT scheduling issue with iso transfer). We detect an error if next == start, but this means uframe 0 can't be allocated anymore for iso transfer... Reported-by: Sander Eikelenboom <linux@eikelenboom.it> Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-11-14USB: EHCI: fix HUB TT scheduling issue with iso transferThomas Poussevin
The current TT scheduling doesn't allow to play and then record on a full-speed device connected to a high speed hub. The IN iso stream can only start on the first uframe (0-2 for a 165 us) because of CSPLIT transactions. For the OUT iso stream there no such restriction. uframe 0-5 are possible. The idea of this patch is that the first uframe are precious (for IN TT iso stream) and we should allocate the last uframes first if possible. For that we reverse the order of uframe allocation (last uframe first). Here an example : hid interrupt stream ---------------------------------------------------------------------- uframe | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | ---------------------------------------------------------------------- max_tt_usecs | 125 | 125 | 125 | 125 | 125 | 125 | 30 | 0 | ---------------------------------------------------------------------- used usecs on a frame | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ---------------------------------------------------------------------- iso OUT stream ---------------------------------------------------------------------- uframe | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | ---------------------------------------------------------------------- max_tt_usecs | 125 | 125 | 125 | 125 | 125 | 125 | 30 | 0 | ---------------------------------------------------------------------- used usecs on a frame | 13 | 125 | 39 | 0 | 0 | 0 | 0 | 0 | ---------------------------------------------------------------------- There no place for iso IN stream (uframe 0-2 are used) and we got "cannot submit datapipe for urb 0, error -28: not enough bandwidth" error. With the patch this become. iso OUT stream ---------------------------------------------------------------------- uframe | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | ---------------------------------------------------------------------- max_tt_usecs | 125 | 125 | 125 | 125 | 125 | 125 | 30 | 0 | ---------------------------------------------------------------------- used usecs on a frame | 13 | 0 | 0 | 0 | 125 | 39 | 0 | 0 | ---------------------------------------------------------------------- iso IN stream ---------------------------------------------------------------------- uframe | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | ---------------------------------------------------------------------- max_tt_usecs | 125 | 125 | 125 | 125 | 125 | 125 | 30 | 0 | ---------------------------------------------------------------------- used usecs on a frame | 13 | 0 | 125 | 40 | 125 | 39 | 0 | 0 | ---------------------------------------------------------------------- Signed-off-by: Matthieu Castet <matthieu.castet@parrot.com> Signed-off-by: Thomas Poussevin <thomas.poussevin@parrot.com> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-10-18EHCI: workaround for MosChip controller bugAlan Stern
This patch (as1489) works around a hardware bug in MosChip EHCI controllers. Evidently when one of these controllers increments the frame-index register, it changes the three low-order bits (the microframe counter) before changing the higher order bits (the frame counter). If the register is read at just the wrong time, the value obtained is too low by 8. When the appropriate quirk flag is set, we work around this problem by reading the frame-index register a second time if the first value's three low-order bits are all 0. This gives the hardware a chance to finish updating the register, yielding the correct value. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Tested-by: Jason N Pitt <jpitt@fhcrc.org> CC: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-08-22USB: EHCI: remove usages of hcd->stateAlan Stern
This patch (as1483) improves the ehci-hcd driver family by getting rid of the reliance on the hcd->state variable. It has no clear owner and it isn't protected by the usual HCD locks. In its place, the patch adds a new, private ehci->rh_state field to record the state of the root hub. Along the way, the patch removes a couple of lines containing redundant assignments to the state variable. Also, the QUIESCING state simply gets changed to the RUNNING state, because the driver doesn't make any distinction between them. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Jingoo Han <jg1.han@samsung.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>