Atomic mode-setting drivers

[Emil Velikov]

On 4 March 2016 at 16:32, Daniel Vetter <daniel at ffwll.ch> wrote:
> Adding relevant mailing lists and people. Please don't send private
> mails to maintainers ;-)
>
> On Fri, Mar 4, 2016 at 1:47 PM, Chih-Wei Huang <cwhuang at android-x86.org> wrote:
>> Hi Daniel,
>> This is the Android-x86 project.
>> I'm looking for info about atomic mode-setting drivers
>> and then found your presentation at
>> http://www.x.org/wiki/Events/XDC2015/Program/xdc-2015.pdf
>>
>> Especially page 16 talks about the Android support,
>> exactly what I want.
>>
>> It said "no one has an open-source atomic hwc".
>> Actually there is one in the AOSP 6.0 release:
>>
>> https://android.googlesource.com/platform/external/drm_hwcomposer
>>
>> It's developed by the Chromium team.
>> An update repo is here:
>> https://chromium.googlesource.com/chromiumos/drm_hwcomposer
>
> Yup, my presentation is already outdated - the latest one for LCA2016
> mentions that hwc exists.
>
>> Contributing instructions are here:
>> https://sites.google.com/a/chromium.org/dev/contributing-to-drm_hwcomposer
>>
>> We are trying to enable the drm_hwcomposer for Android-x86.
>> However, it requires atomic mode-setting drivers
>> which seems are not ready in the vanilla kernel 4.4,
>> the kernel we are using now.
>>
>> Unfortunately none of us is an expert of kernel drm drivres.
>> Could you give me a brief status of the
>> current atomic mode-setting drivers in vanilla kernel?
>> What are still missing? fences? deadlock?
>> More important, how much effort do we need
>> to make them work with AOSP's drm_hwcomposer?
>
> There's a pile of drivers, but for classic x86 desktop only i915.ko,
> and that is still not yet enabled by default. i915.nuclear_pageflip=1
> will give you experimental atomic support but not sure whether that's
> good enough for hwcomposer.
>
> Fences are being worked on in upstream kernel, but nothing to show
> yet.. Otherwise I don't know what's all needed to make it, I haven't
> had a chance to play around with it yet.
>
Let's not forget the new AMDGPU code that, according to the summary
[1], adds ATOMIC support for newer AMD hardware.

Chih-Wei, there might be an updated branch somewhere you can grab,
sadly I did not find any. Thus you might have to pick the patches off
the mailing list, unless we have a patchwork instance for it somewhere
?

>>
>> More discussion about it can be found in
>> our devel group:
>> https://groups.google.com/d/msg/android-x86-devel/RErWaXk3b7g/g_OSPGf4AwAJ
>
> Please include that mailing list too, to make sure everyone is on board.
>
Not sure why, yet that mailing list is closed for public eyes. Last
time I checked one has to be invited to read or write to it :-(
Props to Chih-Wei I'm on it, although others are sure to get the short
end of the stick.

Regards,
Emil

[1] https://lists.freedesktop.org/archives/dri-devel/2016-February/100524.html