[Mesa-dev] EGL_EXT_*_drm - primary vs render node (Was Re: [Piglit] [PATCH 1/2] egl: Add sanity test for EGL_EXT_device_query (v3))

[James Jones]

On 09/07/2016 04:18 AM, Emil Velikov wrote:
> Hi Mathias,
>
> On 6 September 2016 at 18:32, Mathias Fröhlich
> <Mathias.Froehlich at gmx.net> wrote:
>
>>>  ** EGL_EXT_output_drm
> Correction - the above should read: EGL_EXT_{device,output}_drm
>
>>>  *** Using/exposing the card or render node
>>>  - Extension is designed with EGL streams in mind (using the
>>> primary/card node) while people expect to use to select the rendering
>>> device.
>>>  - Elaborate on the spec and/or introduce EGL_EXT_output{,_drm}_render ?
>>>  *** Exposing EGL_EXT_output{,_drm}{,_render} on EGL implementations
>>> supporting both SW and HW devices
>>>  - Elaborate on the spec(s), add new one for SW devices and/or error
>>> type to distinguish between the current errors and SW devices
>> I do not care about anything built on top of EGL_EXT_output_base or
>> EGL_*_stream_*. From my point of view this is beside.
>>
>>
>> What I do care about is EGL_EXT_platform_device.
>>
> That's precisely what, where and why we want to clarify, correct the
> spec or add a new one.
>
> James, Daniel, can we hear your input on the following ?
>
> The way I read the spec(s) EGL_EXT_device_drm can effectively be
> either the card/primary or render node, while EGL_EXT_output_drm must
> be the card one.
> Can/should we restrict the former to render only, do you see any
> implications that will bring ?
> Or should we just roll out another spec for the "render only" case ?

I had assumed EGL_EXT_device_drm's queries refer to the card/primary, 
and an additional extension could add a token to query the render node. 
When we initially started drafting the extensions, render nodes were 
just being introduced, and I considered adding them as a separate query 
later, but we had no need to identify the render nodes, so I demurred.

If that interpretation sounds OK, we can add corresponding 
clarifications to the specifications.

Thanks,
-James

> Thanks
> Emil
>