[Mesa-dev] [PATCH 3/3] RFC: vulkan/wsi: Rework the way prime support works

[Jason Ekstrand]

On Thu, Nov 16, 2017 at 3:47 AM, Mike Lothian <mike at fireburn.co.uk> wrote:

> Will this allow us to select between iGPU and dGPU like we can with
> OpenGL? Or is it just going to force radv like before?
>

I don't think we have a good selection method yet.


> On Thu, 16 Nov 2017 at 10:09 Grazvydas Ignotas <notasas at gmail.com> wrote:
>
>> On Thu, Nov 16, 2017 at 12:33 AM, Dave Airlie <airlied at gmail.com> wrote:
>> > On 15 November 2017 at 04:40, Jason Ekstrand <jason at jlekstrand.net>
>> wrote:
>> >> This commit significantly reworks the way prime support works and lets
>> >> us pull it even further into radv.  The old mechanism required the
>> >> specific WSI layer to be aware of the linear shadow copy that has to be
>> >> done in order for prime to work.  In the new paradigm, we better define
>> >> what bits of wsi_image go to the client and what bits go off to the
>> >> window system.  It's then the job of the driver to allocate two
>> separate
>> >> images and stash whatever intermediates it needs in driver_private.
>> >> There are a few advantages to this method:
>> >>
>> >>  1) It separates supporting prime from the driver decision as to
>> whether
>> >>     it's better to render directly into the window-system-compatible
>> >>     image or if it's better to blit.
>> >>
>> >>  2) Because of this separation, it's now possible for a driver to use a
>> >>     different scheme for WSI image presentation where it hooks the
>> >>     vkCmdPipelineBarrier that transitions the image to
>> >>     VK_IMAGE_LAYOUT_PRESENT_SRC_KHR and does the blit there.
>> >>
>> >>  3) It lets us pull more of the details into radv and, in my opinion,
>> >>     actually makes the radv code more straightforward.
>> >
>> > For the record, PRIME is not radv specific, stop trying to make it so,
>> > anv should support display to other GPUs.
>>
>> Yes it would be great if that worked, would make radv vs anv testing
>> so much easier as I much prefer my display to be on dGPU.
>>
>
Before this conversation goes much further, I think I should say that this
patch is getting scrapped entirely.  Dave and I spent a bunch of time
yesterday rewriting the universe of Vulkan WSI to move in the direction of
more common code.  One of the natural fall-outs of that is that anv gets
prime support for free.

--Jason
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