Re: [PATCH 5/6] drm: vkms: Prepare `vkms_wb_encoder_atomic_check` to accept multiple formats

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 18.10.21 um 19:41 schrieb Igor Matheus Andrade Torrente:
> Hello,
>
> On 10/18/21 7:14 AM, Thomas Zimmermann wrote:
> > Hi
> >
> > Am 05.10.21 um 22:16 schrieb Igor Matheus Andrade Torrente:
> > > Currently, the vkms atomic check only goes through the first position of
> > > the `vkms_wb_formats` vector.
> > >
> > > This change prepares the atomic_check to check the entire vector.
> > >
> > > Signed-off-by: Igor Matheus Andrade Torrente <igormtorrente@xxxxxxxxx>
> > > ---
> > >   drivers/gpu/drm/vkms/vkms_writeback.c | 11 ++++++++++-
> > >   1 file changed, 10 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/vkms/vkms_writeback.c 
> > > b/drivers/gpu/drm/vkms/vkms_writeback.c
> > > index 5a3e12f105dc..56978f499203 100644
> > > --- a/drivers/gpu/drm/vkms/vkms_writeback.c
> > > +++ b/drivers/gpu/drm/vkms/vkms_writeback.c
> > > @@ -30,6 +30,8 @@ static int vkms_wb_encoder_atomic_check(struct 
> > > drm_encoder *encoder,
> > >   {
> > >       struct drm_framebuffer *fb;
> > >       const struct drm_display_mode *mode = &crtc_state->mode;
> > > +    bool format_supported = false;
> > > +    int i;
> > >       if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
> > >           return 0;
> > > @@ -41,7 +43,14 @@ static int vkms_wb_encoder_atomic_check(struct 
> > > drm_encoder *encoder,
> > >           return -EINVAL;
> > >       }
> > > -    if (fb->format->format != vkms_wb_formats[0]) {
> > > +    for (i = 0; i < ARRAY_SIZE(vkms_wb_formats); i++) {
> > > +        if (fb->format->format == vkms_wb_formats[i]) {
> > > +            format_supported = true;
> > > +            break;
> > > +        }
> > > +    }
> >
> > At a minimum, this loop should be in a helper function. But more 
> > generally, I'm surprised that this isn't already covered by the DRM's 
> > atomic helpers.
>
> Ok, I can wrap it in a new function.
>
> AFAIK the DRM doesn't cover it. But I may be wrong...

I couldn't find anything either.

Other drivers do similar format and frambuffer checks. So I guess a 
helper could be implemented. All plane's are supposed to call 
drm_atomic_helper_check_plane_state() in their atomic_check() code. You 
could add a similar helper, say 
drm_atomic_helper_check_writeback_encoder_state(), that tests for the 
format and maybe other things as well.

Best regards
Thomas

> > Best regards
> > Thomas
> >
> > > +
> > > +    if (!format_supported) {
> > >           DRM_DEBUG_KMS("Invalid pixel format %p4cc\n",
> > >                     &fb->format->format);
> > >           return -EINVAL;

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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