linux-kernel - Re: [PATCH] drm/radeon: Fix Asus M2A-VM HDMI EDID error flooding problem

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Message-ID: <CADnq5_M2yy2aota_mbvq4jKns-sQBOLfJrOzQuNOREw=FfgfOg@mail.gmail.com>
Date:	Wed, 6 Jul 2011 11:42:42 -0400
From:	Alex Deucher <alexdeucher@...il.com>
To:	reimth@...glemail.com
Cc:	Dave Airlie <airlied@...hat.com>,
	Mario Kleiner <mario.kleiner@...bingen.mpg.de>,
	Jean Delvare <khali@...ux-fr.org>,
	Tyson Whitehead <twhitehead@...il.com>,
	Jason Wessel <jason.wessel@...driver.com>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Thomas Reim <rdratlos@...oo.co.uk>
Subject: Re: [PATCH] drm/radeon: Fix Asus M2A-VM HDMI EDID error flooding problem

On Wed, Jul 6, 2011 at 11:39 AM, Alex Deucher <alexdeucher@...il.com> wrote:
> On Wed, Jul 6, 2011 at 6:09 AM,  <reimth@...glemail.com> wrote:
>> From: Thomas Reim <rdratlos@...oo.co.uk>
>>
>>    Some integrated ATI Radeon chipset implementations
>>    with add-on HDMI card (e. g. Asus M2A-VM HDMI) indicate the availability
>>    of a DDC even when the add-on card is not plugged in or HDMI is disabled
>>    in BIOS setup. In this case, drm_get_edid() and drm_edid_block_valid()
>>    periodically dump data and kernel errors into system log files and onto
>>    terminals. For these chipsets DDC probing is extended by a check for a
>>    correct EDID header. Only in case a valid EDID header is also found, the
>>    (HDMI) connector will be used by the Radeon driver. This prevents the
>>    kernel driver from useless flooding of logs and terminal sessions with
>>    EDID dumps and error messages.
>>    This patch adds a flag 'requires_extended_probe' to the radeon_connector
>>    structure. In function radeon_connector_needs_extended_probe() this flag
>>    can be set on a chipset family/vendor/connector type specific basis.
>>    In addition, function drm_edid_header_is_valid() has been added for EDID
>>    header check and function radeon_ddc_probe() has been adapted to perform
>>    extended DDC probing if required by the connector's flag.
>>
>>    Tested for kernel 2.35, 2.38 and 3.0 on Asus M2A-VM HDMI board
>>
>
> Once it's ready, just add:
> Cc: stable@...nel.org
> to the commit message and it will go into the stable kernels as well.
> Might want to mention the bug report in your commit message as well.
> Just a couple comments below.  With those fixed:
>
> Reviewed-by: Alex Deucher <alexdeucher@...il.com>

We also may want to revert 4a9a8b71e12d41abb71c4e741bff524f016cfef4
once this patch goes in, otherwise we may remove the ddc bus
unnecessarily on some systems.

Alex
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