[Intel-gfx] [PATCH] drm/i915: Use the first mode if there is no preferred mode in the EDID

[Knut Petersen]

On 13.05.2014 22:24, Jesse Barnes wrote:
> On Tue, 13 May 2014 16:50:12 +0100
> Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
>> On Tue, May 13, 2014 at 04:07:37PM +0100, Chris Wilson wrote:
>>> This matches the algorithm used by earlier kernels when selecting the
>>> mode for the fbcon. And only if there is no modes at all, do we fall
>>> back to using the BIOS configuration. Seamless transition is still
>>> preserved (from the BIOS configuration to ours) so long as the BIOS has
>>> also chosen what we hope is the native configuration.
>>>
>>> Reported-by: Knut Petersen <Knut_Petersen at t-online.de>
>>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78655
>>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>>> Cc: stable at vger.kernel.org
I don't think that  Cc: stable at vger.kernel.org is necessary, kernels up to 3.14.x don't
expose the problem. And as this fixes a post-3.14 regression this is a clear candidate for
3.15

>>> ---
>>>   drivers/gpu/drm/i915/intel_fbdev.c | 8 ++++++++
>>>   1 file changed, 8 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
>>> index 1d3f0a9cce31..05beec4badd5 100644
>>> --- a/drivers/gpu/drm/i915/intel_fbdev.c
>>> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
>>> @@ -397,6 +397,14 @@ static bool intel_fb_initial_config(struct drm_fb_helper *fb_helper,
>>>   							  height);
>>>   		}
>>>   
>>> +		/* No preferred mode marked by the EDID? Are there any modes? */
>>> +		if (!modes[i] && !list_empty(&connector->modes)) {
>>> +			DRM_DEBUG_KMS("using first mode listed on connector %s\n",
>>> +				      drm_get_connector_name(connector));
>>> +			modes[i] = list_first_entry(struct drm_display_mode,
>>> +						    &connector->modes, head);
>> Please imagine that I wrote this correctly.
> Imagining you wrote it correctly:
> Reviewed-by: Jesse Barnes <jbarnes at virtuousgeek.org>

After proper imagination Tested-by: Knut Petersen <Knut_Petersen at t-online.de>.