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

[Alex Deucher]

On Wed, Jul 6, 2011 at 11:39 AM, Alex Deucher <alexdeucher at gmail.com> wrote:
> On Wed, Jul 6, 2011 at 6:09 AM,  <reimth at googlemail.com> wrote:
>> From: Thomas Reim <rdratlos at yahoo.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 at kernel.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 at gmail.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