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authorStefan Richter <stefanr@s5r6.in-berlin.de>2009-12-26 01:35:14 +0100
committerStefan Richter <stefanr@s5r6.in-berlin.de>2009-12-29 19:58:17 +0100
commit090699c0530ae5380a9b8511d76f656cc437bb6e (patch)
tree395c61692df693e6562446b2d23b06793f87a0a4
parentcf0e575dcc4cab9fd955e9bec49df7e8ee30a7cf (diff)
downloadvexpress-lsk-090699c0530ae5380a9b8511d76f656cc437bb6e.tar.gz
firewire: ohci: always use packet-per-buffer mode for isochronous reception
This is a minimal change meant for the short term: Never set the ohci->use_dualbuffer flag to true. There are two reasons to do so: - Packet-per-buffer mode and dual-buffer mode do not behave the same under certain circumstances, notably if several packets are covered by a single fw_cdev_iso_packet descriptor. http://marc.info/?l=linux1394-devel&m=124965653718313 Therefore the driver stack should not silently choose one or the other mode but should leave the choice to the high-level driver (regardless if kernel driver or userspace driver). Or simply always only offer packet-per-buffer mode, since a considerable number of controllers, even current ones, does not offer dual-buffer support. - Even under circumstances where packet-per-buffer mode and dual-buffer mode behave exactly the same --- notably when used through libraw1394, libdc1394, as well as the current two kernel drivers which use isochronous reception (firewire-net and firedtv) --- we are still faced with the problem that several OHCI 1.1 controllers have bugs in dual-buffer mode. Although it looks like we have identified most of those buggy controllers by now, we cannot be quite sure about that. So, use packet-per-buffer by default from now on. This change should be followed up by a more complete solution: Either extend the in-kernel API and the userspace ABI by a choice between the two IR modes or remove all dual-buffer related code from firewire-ohci. Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
-rw-r--r--drivers/firewire/ohci.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 96768e16086..a61571c63c5 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -2226,7 +2226,6 @@ static int ohci_queue_iso_receive_dualbuffer(struct fw_iso_context *base,
if (rest == 0)
return -EINVAL;
- /* FIXME: make packet-per-buffer/dual-buffer a context option */
while (rest > 0) {
d = context_get_descriptors(&ctx->context,
z + header_z, &d_bus);
@@ -2470,7 +2469,10 @@ static int __devinit pci_probe(struct pci_dev *dev,
}
version = reg_read(ohci, OHCI1394_Version) & 0x00ff00ff;
+#if 0
+ /* FIXME: make it a context option or remove dual-buffer mode */
ohci->use_dualbuffer = version >= OHCI_VERSION_1_1;
+#endif
/* dual-buffer mode is broken if more than one IR context is active */
if (dev->vendor == PCI_VENDOR_ID_AGERE &&