Bug 10080

Summary of latest feedback (http://lkml.org/lkml/2008/2/23/244 + http://lkml.org/lkml/2008/2/23/259):
  - The presence of both ohci1394 and firewire-ohci does not seem to be the problem.
  - Several or all of ohci1394's MMIO reads return ~0 (all bits set to one).  Therefore it is unlikely that the problem is caused by the IEEE1394 subsystem.
  - Is this really a regression relative to 2.6.24?

Thomas, can you verify if 2.6.24 works correctly, please?

Thomas response in http://marc.info/?l=linux-kernel&m=120396387509950 :
  - Was apparently a mixup when building the kernel; went away after "make clean".
  - In any case, 2.6.24 was not affected.

New status:  Bug reappeared with a make distclean; make on v2.6.25-rc6-14-gbde4f8f.

Created attachment 15396 [details]
config used

Created attachment 15397 [details]
dmesg

 $ git describe
v2.6.25-rc6-243-g028011e

Handled-By : Nobody

I'm confused about this.  I looked at the original threads, and what really stands out to me is that the original reporter had two drivers loaded for the same hardware (firewire-ohci and ohci1394.)  *In the best case* there is a fundamental race condition there, meaning unpredictable behaviour would be the norm.

Can someone publish the "lspci -vv" for the affected system?

Reply-To: stefanr@s5r6.in-berlin.de

H. Peter Anvin wrote at 
http://bugzilla.kernel.org/show_bug.cgi?id=10080#c9 :
> I'm confused about this.  I looked at the original threads, and what really
> stands out to me is that the original reporter had two drivers loaded for the
> same hardware (firewire-ohci and ohci1394.)  *In the best case* there is a
> fundamental race condition there, meaning unpredictable behaviour would be
> the
> norm.


Hmm, right -- I didn't see this until now.  Today's dmesg:
http://bugzilla.kernel.org/attachment.cgi?id=15397&action=view
[    1.236587] firewire_ohci: Failed to remap registers
[  243.640549] ohci1394: fw-host0: Get PHY Reg timeout
(etc.)

However, the two drivers for the same device don't seem to be the 
problem.  Looks like firewire-ohci was attempted to be bound to the 
controller much earlier than ohci1394.  The error message means that 
firewire-ohci's pci_request_region() succeeded but pci_iomap() failed, 
hence the pci_driver.probe failed, hence firewire-ohci wasn't bound to 
the device, hence subsequent loading of ohci1394 (manually, I presume) 
was a valid action.

IOW firewire-ohci was indeed already loaded, but not bound to the device 
because of the .probe failure; and ohci1394 was loaded much later.

Same thing in the report in February:
http://lkml.org/lkml/2008/2/23/244
[    1.326958] firewire_ohci: Failed to remap registers
[  856.943807] ohci1394: fw-host0: Get PHY Reg timeout
(here: ohci1394 manually loaded by insmod)

(Let's see if bugme-daemon captures this...)

Proposed patch: http://lkml.org/lkml/2008/3/22/175

Created attachment 15417 [details]
lspci -vv

Linus' patch as per comment #12 has been committed:
commit b9e76a00749521f2b080fa8a4fb15f66538ab756
(I suppose it still needs to be tested by Thomas)

Additional proposed patch by Ingo: http://lkml.org/lkml/2008/3/25/32

Created attachment 15433 [details]
dmesg 2.6.24

Created attachment 15434 [details]
lspci -vv 2.6.24

Created attachment 15435 [details]
lsmod 2.6.24

Fixed by: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=12c22d6ef299ccf0955e5756eb57d90d7577ac68