Messages in this thread | | | Date | Sat, 5 Nov 2005 19:39:39 +0200 | From | Matti Aarnio <> | Subject | Re: I2C regression in post 2.6.14 gits.. -- get_user_pages() is real bug.. |
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On Fri, Nov 04, 2005 at 10:29:34AM +0100, Jean Delvare wrote: > Hi Matti, > > On 2005-11-04, Matti Aarnio wrote: > > Specifically, BTTV driver fails to control internal > > I2C devices in Hauppauge WinTV card with Bt848 onboard. > > Can you detail how you came up with this diagnosis? > > > Baseline 2.6.14 works fine, but 2.6.14-git2 fails. > > Can you please try 2.6.14-git1 and 2.6.14-rc5-mm1? This should help us > norrow the faulty patch. Also, please confirm that 2.6.14-git7 still has > the problem. > > > Any ideas ? Possible fixes ? > > Enable as many debugging as possible, in particular I2C Core debugging > (I2C_DEBUG_CORE=y) in a working kernel and a non-working kernel, and > send both logs for comparison. > > Thanks a lot for testing, BTW.
Since then I have been tracking of what really fails in the bttv driver, and running: strace -o tvtime.log tvtime Result is most revealing in failures.
The fault is not in I2C, but appears in video_buf module failing calls of get_user_pages() with -EFAULT.
There has been lots of discussion about it back in August, but apparently only now in post 2.6.14 the changes made it into mm/memory.c which faulted this thing for BTTV.
Oh yes, I do use Fedora Core development kernels, and don't usually (anymore) compile things myself, but now I had a weekend off...
> -- > Jean Delvare
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