[PATCH hwc v2 1/6] drm_hwcomposer: Remove threading

[Rob Herring]

On Thu, Sep 28, 2017 at 11:43 AM, Chih-Wei Huang
<cwhuang at android-x86.org> wrote:
> 2017-09-27 19:58 GMT+08:00 Robert Foss <robert.foss at collabora.com>:
>> From: Sean Paul <seanpaul at chromium.org>
>>
>> Since HWC2 doesn't require the use of threads to implement correct
>> synchronization, remove some of these threads.
>
> May I ask to avoid HWC2 only implementation?
> The main reason is not all GPUs support
> drm_hwcompser (as discussed in another thread).

Which thread? Is that because they don't support explicit fences? Or
something else?

> To continue supporting these GPUs we need to
> keep using HWC1 version of SurfaceFlinger.

I think that is a lot of complexity to keep which will impact future
changes as well. For example, is keeping it going to make removing
sw_sync dependency (A non-stable debugfs interface) more difficult?
drm_hwcomposer is already complex enough IMO with the GL compositing
that removing some complexity would be a good thing.

> So it's better to keep the code compatible with
> HWC1. At least make it be a compile-time option.
>
> Personally I have a patch to make
> HWC1 vs HWC2 a compile-time choice
> of drm_hwcomposer.

Perhaps just leave the current state as a separate branch.

> I can submit it if it's acceptable.
>
>
> --
> Chih-Wei
> Android-x86 project
> http://www.android-x86.org