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| author | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2009-12-26 01:35:14 +0100 |
|---|---|---|
| committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2009-12-29 19:58:17 +0100 |
| commit | 090699c0530ae5380a9b8511d76f656cc437bb6e (patch) | |
| tree | 395c61692df693e6562446b2d23b06793f87a0a4 /drivers | |
| parent | cf0e575dcc4cab9fd955e9bec49df7e8ee30a7cf (diff) | |
| download | op-kernel-dev-090699c0530ae5380a9b8511d76f656cc437bb6e.zip op-kernel-dev-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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/firewire/ohci.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index 96768e1..a61571c 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 && |
