[PATCH] Add aspect-ratio support in wayland layer.

Sharma, Shashank shashank.sharma at intel.com
Mon Sep 11 09:06:13 UTC 2017

Hello Pekka

Thanks for your review comments and constructive discussions with Ankit 
on IRC.
I am Shashank from Intel, I am guiding Ankit on this activity.  I have 
few comments (inline),
it would be great if you can let us know your view on this.

On 9/8/2017 7:43 PM, Pekka Paalanen wrote:
> On Wed,  6 Sep 2017 17:50:00 +0530
> Nautiyal Ankit <ankit.k.nautiyal at intel.com> wrote:
>> From: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
>> This patch series adds video mode aspect ratio support for
>> wayland protocol and weston drm compositor. This patch series
>> adds two patches:
>> 1- Adds aspect ratio flag bits bits in wl_output_mode flags
>> as per DRM layer implementation.
>> 2- Preserves and uses the aspect ratio flags while selecting
>> the mode for modeset in weston drm compositor.
>> The corresponding kernel implementation for the aspect ratio support
>> in DRM Layer can be found here:
>> https://patchwork.freedesktop.org/series/10850/
>> This is a four patch series, in which two patches are already
>> merged, and two are waiting for user space implementation.
> Hi,
> we discussed these patches on #wayland in IRC, and I believe we came to
> the following conclusion:
> - Let's not add to wayland.xml, and not advertise the aspect ratio to
>    clients. There is no need to do this, and clients are currently not
>    able to take advantage of it either.
- In this case, how to decide what should be the aspect ratio of the 
output mode and based on what ?
   For example If a CEA mode is available for 16:9 and 4:3 aspects, 
which one to pick and how ? If we don't
   get inputs from the client, we would be picking the first mode in the 
list which might not be the best practice.
- While supporting advance display outputs like HDMI 2.0 / UHD, when the 
content can be in super wide aspect
    like 64:27 for movies/game, wouldn't it be under utilization of 
display capabilities not to pick it ?

- Shashank
> - With the wl_output bits dropped, the idea in the Weston patch is
>    good. You are adding a way to choose non-square pixel modes via
>    weston.ini, and to choose the refresh rate as well.
> The purpose of the Weston patch is to provide a real test vehicle for
> the remaining kernel patches. The above mentioned should suffice, I
> believe.
> Thanks,
> pq

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