From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH] drm/i915: enforce bitbanging for i2c
Date: Tue, 21 Aug 2012 11:07:54 +0200
Message-ID: <20120821090754.GD5156@phenom.ffwll.local>
References: <1345538269-27765-1-git-send-email-daniel.vetter@ffwll.ch>
	<87txvwboqy.fsf@intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org>
Received: from mail-ey0-f177.google.com (mail-ey0-f177.google.com
	[209.85.215.177])
	by gabe.freedesktop.org (Postfix) with ESMTP id 9079B9EFDF
	for <intel-gfx@lists.freedesktop.org>;
	Tue, 21 Aug 2012 02:07:31 -0700 (PDT)
Received: by eaai12 with SMTP id i12so1953315eaa.36
	for <intel-gfx@lists.freedesktop.org>;
	Tue, 21 Aug 2012 02:07:30 -0700 (PDT)
Content-Disposition: inline
In-Reply-To: <87txvwboqy.fsf@intel.com>
List-Unsubscribe: <http://lists.freedesktop.org/mailman/options/intel-gfx>,
	<mailto:intel-gfx-request@lists.freedesktop.org?subject=unsubscribe>
List-Archive: <http://lists.freedesktop.org/archives/intel-gfx>
List-Post: <mailto:intel-gfx@lists.freedesktop.org>
List-Help: <mailto:intel-gfx-request@lists.freedesktop.org?subject=help>
List-Subscribe: <http://lists.freedesktop.org/mailman/listinfo/intel-gfx>,
	<mailto:intel-gfx-request@lists.freedesktop.org?subject=subscribe>
Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org
Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org
To: Jani Nikula <jani.nikula@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>, Intel Graphics Development <intel-gfx@lists.freedesktop.org>, stable@vger.kernel.org
List-Id: intel-gfx@lists.freedesktop.org

On Tue, Aug 21, 2012 at 12:03:49PM +0300, Jani Nikula wrote:
> On Tue, 21 Aug 2012, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> > Now that we have also have a workaround for crt to fallback to
> > bitbanging in some cases and then restore gmbus again, we need to
> > ensure that we don't try to enable gmbus on broken hw (like i830M).
> > Previously only sdvo had a bit-banging fallback, and sdvo is gen3+
> > only, so no issue with that.
> >
> > Enforce this by tracking separately whether gmbus even could work.
> >
> > This issue has been introduced in
> >
> > commit f1a2f5b7c5f0941d23eef0a095c0b99bf8d051e6
> > Author: Jani Nikula <jani.nikula@intel.com>
> > Date:   Mon Aug 13 13:22:35 2012 +0300
> >
> >     drm/i915: fall back to bit-banging if GMBUS fails in CRT EDID
> >     reads
> >
> > Found by code-inspection, no bug report afaik.
> 
> I don't see how my patch could enable or try GMBUS if force_bit has been
> set to true. On i830 the first attempt will be bit-banging, as before,
> and there will be no fallback because bit-banging is already enabled.
> 
> I don't think this patch is necessary, but by all means prove me
> wrong. ;)

Right, I've missed the is_force_bit check in intel_crt_get_edid, patch is
not required.

/me hides

Cheers, Daniel
-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48