[Mesa-dev] [RFC] OES_external_image for i965

[Kristian Høgsberg]

On Mon, Mar 4, 2013 at 10:11 AM, Pohjolainen, Topi
<topi.pohjolainen at intel.com> wrote:
> On Mon, Mar 04, 2013 at 09:56:34AM -0500, Kristian H?gsberg wrote:
>> On Mon, Mar 4, 2013 at 4:55 AM, Pohjolainen, Topi
>> <topi.pohjolainen at intel.com> wrote:
>> > On Fri, Mar 01, 2013 at 10:03:45AM -0500, Kristian H?gsberg wrote:
>> >> On Fri, Mar 1, 2013 at 3:51 AM, Pohjolainen, Topi
>> >> <topi.pohjolainen at intel.com> wrote:
>> >> > On Tue, Feb 26, 2013 at 04:05:25PM +0000, Tom Cooksey wrote:
>> >> >> Hi Topi,
>> >> >>
>> >> >> > The second more or less questionable part is the support for creating YUV
>> >> >> > buffers. In order to test for YUV sampling one needs a way of providing them
>> >> >> > for the EGL stack. Here I chose to augment the dri driver backing gbm as I
>> >> >> > couldn't come up with anything better. It may be helpful to take a look at the
>> >> >> > corresponding piglit test case and framework support I've written for it.
>> >> >>
>> >> >> You might want to take a look at the EGL_EXT_image_dma_buf_import[i] which has been written
>> >> >> specifically for this purpose. Though this does assume you have a driver which supports exporting a
>> >> >> YUV buffer it has allocated with dma_buf, such as a v4l2 driver or even ion on Android.
>> >> >>
>> >> >
>> >> > It certainly looks good addressing not only the individual plane setup but
>> >> > allowing one to control also the conversion coefficients and subsampling
>> >> > position.
>> >> > Coming from piglit testing point of view, do you have any ideas where to
>> >> > allocate the buffers from? I guess people wouldn't be too happy seeing v4l2 tied
>> >> > into piglit, for example.
>> >>
>> >> SInce you're already using intel specific ioctls to mmap the buffers,
>> >> I'd suggest you just go all the way and allocate using intel specific
>> >> ioctls (like my simple-yuv.c example).  I don't really see any other
>> >> approach, but it's not pretty...
>> >>
>> >
>> > I used gbm buffer objects in order to match the logic later in
>> > 'dri2_drm_create_image_khr()' which expects the buffer to be of the type
>> > 'gbm_dri_bo' (gbm_bo) for the target EGL_NATIVE_PIXMAP_KHR. Giving drm buffer
>> > objects instead would require new target, I guess?
>>
>> Right... I'd use the extension Tom suggests:
>>
>> http://www.khronos.org/registry/egl/extensions/EXT/EGL_EXT_image_dma_buf_import.txt
>>
>> which is mostly implemented by this patch:
>>
>> http://lists.freedesktop.org/archives/mesa-dev/2013-February/035429.html
>>
>> with just the EGL extension bits missing.  That way, you're also not
>> dependent on any specific window system.  As it is your test has to
>> run under gbm, using the dmabuf import extension it can run under any
>> window system.
>
> Just to clarify that I understood correctly. The actual creation of the buffer
> (and dma_buf exporting) would still be via hardware specific ioctls (in intel's
> case GEM)? Your and Tom's material address only the importing side, or did I
> miss something?

Yes, that's correct.  You'll need intel create and export to fd
functions, but you are already mapping the bo using intel specific
ioctls.  So I think it's cleaner to just have a chipset specific
function to create the bo and return an fd, stride etc, and from there
on it's generic code where you feed it into the dma_buf_import
function.

Kristian