[Intel-gfx] [PATCH] drm/i915/edp: Only use alternate fixed mode when requested

[Clint Taylor]

On 04/11/2018 04:11 PM, Chris Wilson wrote:
> Quoting clinton.a.taylor at intel.com (2018-04-12 00:13:26)
>> From: Clint Taylor <clinton.a.taylor at intel.com>
>>
>> In commit dc911f5bd8aa ("drm/i915/edp: Allow alternate fixed mode for eDP
>> if available."), the patch was always selecting the alternate refresh rate
>> even though user space was asking for the higher rate. This patch adds a
>> check for vrefresh rate as well as the rest of the mode geometry.
>>
>> V2: use clock instead of vrefresh for compare.
>>
>> Fixes: dc911f5bd8aac ("Allow alternate fixed mode for eDP if available.")
>> Cc: David Weinehall <david.weinehall at linux.intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
>> Signed-off-by: Clint Taylor <clinton.a.taylor at intel.com>
> Still leaves the other discussion point in the other thread unresolved.
> The fields are supplied by the user and can be arbitrary, so if they
> request a clock for a 30Hz mode, instead of using the 40Hz alternative,
> we use the 60Hz normal mode (by way of example). Is equality always the
> best choice here?
This feature is for testing PSR panels that don't support single frame 
setup times in their preferred timing. The down-clocked mode is the 
timing that the panel specifically states is supported. If a customer 
specifies a custom mode either it should be rejected or the eDP fixed 
mode (preferred) should be used. If we want to allow the users to set a 
custom timing to their eDP panels then we should get rid of the fixed 
mode feature for eDP panels.

-Clint

> -Chris