Re: [PATCH] drm/i915: make edp optimize config

[Benson Leung <bleung@google.com>]

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Hi Matt,

Minor commit message nits.

On Thu, Mar 08, 2018 at 05:17:38PM -0800, matthew.s.atwood@intel.com wrote:
> From: Matt Atwood <matthew.s.atwood@intel.com>
> 
> Previously it was assumed that eDP panels would advertise the lowest link
> rate required for their singular mode to function. With the introduction
> of more advanced features there are advantages to a panel advertising a
> higher rate then
s/then/than

> it needs for a its given mode. 

Don't need "its" here.

> For panels that did, the
> driver previously used a higher rate then necessary for that mode.
>
s/then/than

 
> Signed-off-by: Matt Atwood <matthew.s.atwood@intel.com>

Tested-by: Benson Leung <bleung@chromium.org>

Tested this on a panel and system with the following source and sink rates:


[    1.623225] [drm:intel_dp_print_rates] source rates: 162000, 216000, 270000, 324000, 432000, 540000
[    1.623230] [drm:intel_dp_print_rates] sink rates: 162000, 216000, 243000, 270000, 324000, 432000, 540000
[    1.623234] [drm:intel_dp_print_rates] common rates: 162000, 216000, 270000, 324000, 432000, 540000

Prior to this patch, the driver would pick and train at 540000:
[    2.865653] [drm:intel_dp_start_link_train] [CONNECTOR:76:eDP-1] Link Training Passed at Link Rate = 540000, Lane count = 4

After this patch, the driver picks and trains at 324000, which is enough
for the panel's native mode:
[    5.359499] [drm:intel_dp_start_link_train] [CONNECTOR:76:eDP-1] Link Training Passed at Link Rate = 324000, Lane count = 4

Thanks!
Benson

-- 
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@google.com
Chromium OS Project
bleung@chromium.org

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