path: root/drivers/usb/host/ehci-timer.c
diff options
authorAlan Stern <stern@rowland.harvard.edu>2012-07-11 11:22:49 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-07-16 16:56:47 -0700
commit3c273a056bf46167f0a1309c2ba72282a17d2541 (patch)
tree91938cb7d5b087567420384a7c4438eb1b7f0252 /drivers/usb/host/ehci-timer.c
parent9d9387475af261949f61a5ec465e1f762d7be08a (diff)
USB: EHCI: unlink multiple async QHs together
This patch (as1582) changes ehci-hcd's strategy for unlinking async QHs. Currently the driver never unlinks more than one QH at a time. This can be inefficient and cause unnecessary delays, since a QH cannot be reused while it is waiting to be unlinked. The new strategy unlinks all the waiting QHs at once. In practice the improvement won't be very big, because it's somewhat uncommon to have two or more QHs waiting to be unlinked at any time. But it does happen, and in any case, doing things this way makes more sense IMO. The change requires the async unlinking code to be refactored slightly. Now in addition to the routines for starting and ending an unlink, there are new routines for unlinking a single QH and starting an IAA cycle. This approach is needed because there are two separate paths for unlinking async QHs: When a transfer error occurs or an URB is cancelled, the QH must be unlinked right away; When a QH has been idle sufficiently long, it is unlinked to avoid consuming DMA bandwidth uselessly. In the first case we want the unlink to proceed as quickly as possible, whereas in the second case we can afford to batch several QHs together and unlink them all at once. Hence the division of labor. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/host/ehci-timer.c')
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index aab042064226..8ca5f152f5bd 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -211,6 +211,7 @@ static void ehci_handle_controller_death(struct ehci_hcd *ehci)
ehci_writel(ehci, 0, &ehci->regs->configured_flag);
ehci_writel(ehci, 0, &ehci->regs->intr_enable);
+ end_unlink_async(ehci);
/* Not in process context, so don't try to reset the controller */
@@ -304,7 +305,7 @@ static void ehci_iaa_watchdog(struct ehci_hcd *ehci)
* (a) SMP races against real IAA firing and retriggering, and
* (b) clean HC shutdown, when IAA watchdog was pending.
- if (ehci->async_unlink) {
+ if (ehci->async_iaa) {
u32 cmd, status;
/* If we get here, IAA is *REALLY* late. It's barely