Re: [PATCH 2/3] drm: Introduce __setplane_atomic()

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On Thu, Jun 28, 2018 at 7:36 PM, Ville Syrjälä
<ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> On Thu, Jun 28, 2018 at 07:05:10PM +0200, Daniel Vetter wrote:
>> On Thu, Jun 28, 2018 at 04:54:56PM +0300, Ville Syrjala wrote:
>> > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>> >
>> > All the plane->fb/old_fb/crtc dance of __setplane_internal() is
>> > pointless on atomic drivers. So let's just introduce a simpler
>> > version that skips all that.
>> >
>> > Ideally we could also skip the __setplane_check() as
>> > drm_atomic_plane_check() already checks for everything, but the
>> > legacy cursor/"async" .update_plane() tricks bypass that so
>> > we still need to call __setplane_check(). Toss in a FIXME to
>> > remind someone to clean this up later.
>> >
>> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>> > ---
>> >  drivers/gpu/drm/drm_plane.c | 68 +++++++++++++++++++++++++++++++++++++--------
>> >  1 file changed, 57 insertions(+), 11 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
>> > index 5c97a0131484..58702340808c 100644
>> > --- a/drivers/gpu/drm/drm_plane.c
>> > +++ b/drivers/gpu/drm/drm_plane.c
>> > @@ -649,6 +649,8 @@ static int __setplane_internal(struct drm_plane *plane,
>> >  {
>> >     int ret = 0;
>> >
>> > +   WARN_ON(plane->state);
>> > +
>> >     /* No fb means shut it down */
>> >     if (!fb) {
>> >             plane->old_fb = plane->fb;
>> > @@ -673,11 +675,9 @@ static int __setplane_internal(struct drm_plane *plane,
>> >                                      crtc_x, crtc_y, crtc_w, crtc_h,
>> >                                      src_x, src_y, src_w, src_h, ctx);
>> >     if (!ret) {
>> > -           if (!plane->state) {
>> > -                   plane->crtc = crtc;
>> > -                   plane->fb = fb;
>> > -                   drm_framebuffer_get(plane->fb);
>> > -           }
>> > +           plane->crtc = crtc;
>> > +           plane->fb = fb;
>> > +           drm_framebuffer_get(plane->fb);
>> >     } else {
>> >             plane->old_fb = NULL;
>> >     }
>> > @@ -690,6 +690,41 @@ static int __setplane_internal(struct drm_plane *plane,
>> >     return ret;
>> >  }
>> >
>> > +static int __setplane_atomic(struct drm_plane *plane,
>> > +                        struct drm_crtc *crtc,
>> > +                        struct drm_framebuffer *fb,
>> > +                        int32_t crtc_x, int32_t crtc_y,
>> > +                        uint32_t crtc_w, uint32_t crtc_h,
>> > +                        uint32_t src_x, uint32_t src_y,
>> > +                        uint32_t src_w, uint32_t src_h,
>> > +                        struct drm_modeset_acquire_ctx *ctx)
>> > +{
>> > +   int ret;
>> > +
>> > +   WARN_ON(!plane->state);
>> > +
>> > +   /* No fb means shut it down */
>> > +   if (!fb)
>> > +           return plane->funcs->disable_plane(plane, ctx);
>> > +
>> > +   /*
>> > +    * FIXME: This is redundant with drm_atomic_plane_check(),
>> > +    * but the legacy cursor/"async" .update_plane() tricks
>> > +    * don't call that so we still need this here. Should remove
>> > +    * this when all .update_plane() implementations have been
>> > +    * fixed to call drm_atomic_plane_check().
>> > +    */
>> > +   ret = __setplane_check(plane, crtc, fb,
>> > +                          crtc_x, crtc_y, crtc_w, crtc_h,
>> > +                          src_x, src_y, src_w, src_h);
>> > +   if (ret)
>> > +           return ret;
>> > +
>> > +   return plane->funcs->update_plane(plane, crtc, fb,
>> > +                                     crtc_x, crtc_y, crtc_w, crtc_h,
>> > +                                     src_x, src_y, src_w, src_h, ctx);
>> > +}
>> > +
>> >  static int setplane_internal(struct drm_plane *plane,
>> >                          struct drm_crtc *crtc,
>> >                          struct drm_framebuffer *fb,
>> > @@ -707,9 +742,15 @@ static int setplane_internal(struct drm_plane *plane,
>> >     ret = drm_modeset_lock_all_ctx(plane->dev, &ctx);
>> >     if (ret)
>> >             goto fail;
>> > -   ret = __setplane_internal(plane, crtc, fb,
>> > -                             crtc_x, crtc_y, crtc_w, crtc_h,
>> > -                             src_x, src_y, src_w, src_h, &ctx);
>> > +
>> > +   if (plane->state)
>>
>> We're not 100% consistent, but I think this here will make life harder for
>> drivers transitioning to atomic. Not many left, but still some.
>>
>> Please use drm_drv_uses_atomic_modeset() instead and check instead for
>> DRIVER_ATOMIC in your WARN_ON in all the places you're checking for
>> ->state in this patch and the next one.
>
> We're already using obj->state as the atomic indicator here,
> so this patch itself isn't changing anything.

Huh, must have missed that when reviewing your legacy state removal series.

> I guess you're suggesting that we change all the ->state checks
> we already have to the uses_atomic() thing instead? And the
> aim is to allow drives to add obj->state before actually
> implementing atomic fully? To me that feels like asking for
> trouble, but who knows, maybe I'm wrong.

Yup that's actually required by the transitional helpers. You start
building up the ->state stuff before it's all fully in place, since
otherwise you have a bit a chicken&egg situation. Which would mean a
full driver rewrite to get to atomic instead of more gradual
transition.

The one exception is the various getfoo ioctls, where the ->state
stuff should be accurate enough as soon as it's there.
-Daniel


>>
>> With that fixed, on the series:
>>
>> Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
>>
>> > +           ret = __setplane_atomic(plane, crtc, fb,
>> > +                                   crtc_x, crtc_y, crtc_w, crtc_h,
>> > +                                   src_x, src_y, src_w, src_h, &ctx);
>> > +   else
>> > +           ret = __setplane_internal(plane, crtc, fb,
>> > +                                     crtc_x, crtc_y, crtc_w, crtc_h,
>> > +                                     src_x, src_y, src_w, src_h, &ctx);
>> >
>> >  fail:
>> >     if (ret == -EDEADLK) {
>> > @@ -841,9 +882,14 @@ static int drm_mode_cursor_universal(struct drm_crtc *crtc,
>> >             src_h = fb->height << 16;
>> >     }
>> >
>> > -   ret = __setplane_internal(plane, crtc, fb,
>> > -                             crtc_x, crtc_y, crtc_w, crtc_h,
>> > -                             0, 0, src_w, src_h, ctx);
>> > +   if (plane->state)
>> > +           ret = __setplane_atomic(plane, crtc, fb,
>> > +                                   crtc_x, crtc_y, crtc_w, crtc_h,
>> > +                                   0, 0, src_w, src_h, ctx);
>> > +   else
>> > +           ret = __setplane_internal(plane, crtc, fb,
>> > +                                     crtc_x, crtc_y, crtc_w, crtc_h,
>> > +                                     0, 0, src_w, src_h, ctx);
>> >
>> >     if (fb)
>> >             drm_framebuffer_put(fb);
>> > --
>> > 2.16.4
>> >
>> > _______________________________________________
>> > dri-devel mailing list
>> > dri-devel@xxxxxxxxxxxxxxxxxxxxx
>> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>
>> --
>> Daniel Vetter
>> Software Engineer, Intel Corporation
>> http://blog.ffwll.ch
>
> --
> Ville Syrjälä
> Intel



-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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