[PATCH weston] simple-dmabuf-drm: use GBM generic calls

Emil Velikov emil.l.velikov at gmail.com
Tue Jul 24 13:45:42 UTC 2018

Hi everyone,

On 11 July 2018 at 09:33, Daniel Stone <daniel at fooishbar.org> wrote:
> Hi,
> On Wed, 11 Jul 2018 at 09:16, Pekka Paalanen <ppaalanen at gmail.com> wrote:
>> On Tue, 10 Jul 2018 17:53:15 +0200 Emilio Pozuelo Monfort <pochu27 at gmail.com> wrote:
>> > No need to write libdrm driver specific code for each supported
>> > driver, we can just let GBM call the right one for us now.
>> >
>> > Signed-off-by: Emilio Pozuelo Monfort <emilio.pozuelo at collabora.co.uk>
>> > ---
>> >
>> > Hi,
>> >
>> > This simplifies the code a lot, using gbm_bo as Emil suggested. Some problems
>> > I still see:
>> >
>> > - NV12 doesn't work, it seems that backends/dri/gbm_dri.c:gbm_format_to_dri_format()
>> >   doesn't support it.
>> I think NV12 and other less common formats, should someone add them in
>> this program, should not be lost. That may be part of the reason GBM
>> wasn't used: the need to test YUV formats, and non-GPU-renderable
>> formats in general.
> Honestly, most of the reason was because I wrote the original client
> in about 15 minutes on a very short bus trip. You can probably see
> that in comments like 'XXX: would be nice to draw something that
> changes here'. So I don't think you can really read too much into the
> original code.
> Other great reasons include:
>   - we wanted to explicitly get modifiers allocated, and this was
> before the GBM modifiers interface existed
>   - at the time, I was doing bring-up of a GBM implementation which
> wasn't usable by generic clients (privileged allocation only)
>   - YUV format support
> I'm pretty ambivalent about it though. V4L2 and Vivid might well cover
> the YUV case well enough, and even if not, GBM should still be able to
> allocate R/RG buffers.
Darn, I did not spot NV12 in weston. Mesa is perfectly capable of
using YUV formats, so it should be a matter of adding the odd GBM

That said, it might be more involving than what you have time for, so
feel free to put this patch on hold.


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