From mboxrd@z Thu Jan 1 00:00:00 1970
From: bugzilla-daemon@freedesktop.org
Subject: [Bug 29787] [RADEON:KMS::EDID] i2c bit banging + preempt kernel ->
i2c failure (random XRandR failures)
Date: Sat, 21 May 2011 04:31:35 -0700 (PDT)
Message-ID: <20110521113135.F40A113004E@annarchy.freedesktop.org>
References:
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path:
Received: from annarchy.freedesktop.org (annarchy.freedesktop.org
[131.252.210.176])
by gabe.freedesktop.org (Postfix) with ESMTP id 224FF9E7F7
for ;
Sat, 21 May 2011 04:31:36 -0700 (PDT)
In-Reply-To:
List-Unsubscribe: ,
List-Archive:
List-Post:
List-Help:
List-Subscribe: ,
Sender: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org
Errors-To: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org
To: dri-devel@lists.freedesktop.org
List-Id: dri-devel@lists.freedesktop.org
https://bugs.freedesktop.org/show_bug.cgi?id=29787
--- Comment #18 from Ville Syrjala 2011-05-21 04:31:35 PDT ---
(In reply to comment #15)
> (In reply to comment #14)
> > Grumble. So, how will this be fixed? Sprinkle the code with
> > preempt_disable()/enable() pairs? Advise all users (well, me) to disable
> > preemption? Change the code so it no longer acts on intermittent EDID failures?
> > Ask your colleagues to design sane hardware that doesn't rely on software
> > interaction for timing-critical operations ;) ?
> >
> > FWIW, I'm perfectly happy to disable preemption in my kernel, haven't run a
> > distro-provided kernel since 2.6.27. But your explanation sounds like this
> > could bite a lot more users than just me.
>
> It has nothing to do with the hw, it's the nature of i2c. All drivers that use
> bit banging i2c (hwmon, v4l, lots of embedded stuff) would potentially be
> affected.
If the EEPROM supports clock stretching I see no reason why bit banging would
fail.
I got these timeout errors on one system at some point. I had an idea for a
possible fix, but I never got around to testing it. I'll attach the patch.
--
Configure bugmail: https://bugs.freedesktop.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.