From: Matti Aarnio <matti.aarnio@zmailer.org>
To: Jean Delvare <khali@linux-fr.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: I2C regression in post 2.6.14 gits.. -- get_user_pages() is real bug..
Date: Sat, 5 Nov 2005 19:39:39 +0200 [thread overview]
Message-ID: <20051105173939.GF3423@mea-ext.zmailer.org> (raw)
In-Reply-To: <Go3tHv2d.1131096574.7056520.khali@localhost>
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
/Matti Aarnio
prev parent reply other threads:[~2005-11-05 17:39 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-02 22:38 I2C regression in post 2.6.14 gits Matti Aarnio
2005-11-04 9:29 ` Jean Delvare
2005-11-05 17:39 ` Matti Aarnio [this message]
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