Re: [PATCH v3 05/18] drm: Add helper to implement legacy dirtyfb

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Oct 11, 2018 at 06:15:47PM +0200, Daniel Vetter wrote:
> On Wed, Oct 10, 2018 at 05:16:44PM -0700, Deepak Rawat wrote:
> > From: Rob Clark <robdclark@gmail.com>
> > 
> > Add an atomic helper to implement dirtyfb support.  This is needed to
> > support DSI command-mode panels with x11 userspace (ie. when we can't
> > rely on pageflips to trigger a flush to the panel).
> > 
> > v2: Modified the helper to use plane fb_damage_clips property and
> > removed plane_state::dirty flag.
> > 
> > v3:
> > - Use uapi drm_mode_rect.
> > - Support annotate flags.
> > 
> > v4: Correct kernel doc.
> > 
> > Cc: ville.syrjala@linux.intel.com
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Pekka Paalanen <ppaalanen@gmail.com>
> > Cc: Daniel Stone <daniel@fooishbar.org>
> > Signed-off-by: Rob Clark <robdclark@gmail.com>
> > Signed-off-by: Deepak Rawat <drawat@vmware.com>
> > ---
> >  drivers/gpu/drm/drm_damage_helper.c | 124 ++++++++++++++++++++++++++++
> >  include/drm/drm_damage_helper.h     |   4 +
> >  2 files changed, 128 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_damage_helper.c b/drivers/gpu/drm/drm_damage_helper.c
> > index e80fa6e08a99..fdb5a072d7e9 100644
> > --- a/drivers/gpu/drm/drm_damage_helper.c
> > +++ b/drivers/gpu/drm/drm_damage_helper.c
> > @@ -26,6 +26,7 @@
> >   *
> >   * Authors:
> >   * Deepak Rawat <drawat@vmware.com>
> > + * Rob Clark <robdclark@gmail.com>
> >   *
> >   **************************************************************************/
> >  
> > @@ -70,6 +71,21 @@
> >   * rectangles clipped to &drm_plane_state.src.
> >   */
> >  
> > +static void convert_clip_rect_to_rect(const struct drm_clip_rect *src,
> > +				      struct drm_mode_rect *dest,
> > +				      uint32_t num_clips, uint32_t src_inc)
> > +{
> > +	while (num_clips > 0) {
> > +		dest->x1 = src->x1;
> > +		dest->y1 = src->y1;
> > +		dest->x2 = src->x2;
> > +		dest->y2 = src->y2;
> > +		src += src_inc;
> > +		dest++;
> > +		num_clips--;
> > +	}
> > +}
> > +
> >  /**
> >   * drm_plane_enable_fb_damage_clips - Enables plane fb damage clips property.
> >   * @plane: Plane on which to enable damage clips property.
> > @@ -123,6 +139,114 @@ void drm_atomic_helper_check_plane_damage(struct drm_atomic_state *state,
> >  }
> >  EXPORT_SYMBOL(drm_atomic_helper_check_plane_damage);
> >  
> > +/**
> > + * drm_atomic_helper_dirtyfb - Helper for dirtyfb.
> > + * @fb: DRM framebuffer.
> > + * @file_priv: Drm file for the ioctl call.
> > + * @flags: Dirty fb annotate flags.
> > + * @color: Color for annotate fill.
> > + * @clips: Dirty region.
> > + * @num_clips: Count of clip in clips.
> > + *
> > + * A helper to implement &drm_framebuffer_funcs::dirty using damage interface
> 
> s/::/./ to make the kerneldoc work.
> 
> > + * during plane update. If num_clips is 0 then this helper will do a full plane
> > + * update. This is the same behaviour expected by dirtyfb ioctl().
> 
> I think usually we all-uppercase DIRTFB IOCTL, but this is also ok I
> think.
> 
> With this addressed:
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> > + *
> > + * Note that this helper is blocking implementation. This is because current
> > + * user of this helper is vmwgfx which needs blocking.

We also know other drivers block here too. I think you could reword this
to not be vmwgfx-specific, e.g. "This is what current drivers and
userspace expect in their DIRTYFB IOCTL implementation, as a way to
rate-limit userspace and make sure its rendering doesn't get ahead of
uploading new data too much."
-Daniel

> > + *
> > + * Return: Zero on success, negative errno on failure.
> > + */
> > +int drm_atomic_helper_dirtyfb(struct drm_framebuffer *fb,
> > +			      struct drm_file *file_priv, unsigned flags,
> > +			      unsigned color, struct drm_clip_rect *clips,
> > +			      unsigned num_clips)
> > +{
> > +	struct drm_modeset_acquire_ctx ctx;
> > +	struct drm_property_blob *damage = NULL;
> > +	struct drm_mode_rect *rects = NULL;
> > +	struct drm_atomic_state *state;
> > +	struct drm_plane *plane;
> > +	int ret = 0;
> > +
> > +	/*
> > +	 * When called from ioctl, we are interruptable, but not when called
> > +	 * internally (ie. defio worker)
> > +	 */
> > +	drm_modeset_acquire_init(&ctx,
> > +		file_priv ? DRM_MODESET_ACQUIRE_INTERRUPTIBLE : 0);
> > +
> > +	state = drm_atomic_state_alloc(fb->dev);
> > +	if (!state) {
> > +		ret = -ENOMEM;
> > +		goto out;
> > +	}
> > +	state->acquire_ctx = &ctx;
> > +
> > +	if (clips) {
> > +		uint32_t inc = 1;
> > +
> > +		if (flags & DRM_MODE_FB_DIRTY_ANNOTATE_COPY) {
> > +			inc = 2;
> > +			num_clips /= 2;
> > +		}
> > +
> > +		rects = kcalloc(num_clips, sizeof(*rects), GFP_KERNEL);
> > +		if (!rects) {
> > +			ret = -ENOMEM;
> > +			goto out;
> > +		}
> > +
> > +		convert_clip_rect_to_rect(clips, rects, num_clips, inc);
> > +		damage = drm_property_create_blob(fb->dev,
> > +						  num_clips * sizeof(*rects),
> > +						  rects);
> > +		if (IS_ERR(damage)) {
> > +			ret = PTR_ERR(damage);
> > +			damage = NULL;
> > +			goto out;
> > +		}
> > +	}
> > +
> > +retry:
> > +	drm_for_each_plane(plane, fb->dev) {
> > +		struct drm_plane_state *plane_state;
> > +
> > +		if (plane->state->fb != fb)
> > +			continue;
> > +
> > +		plane_state = drm_atomic_get_plane_state(state, plane);
> > +		if (IS_ERR(plane_state)) {
> > +			ret = PTR_ERR(plane_state);
> > +			goto out;
> > +		}
> > +
> > +		drm_property_replace_blob(&plane_state->fb_damage_clips,
> > +					  damage);
> > +	}
> > +
> > +	ret = drm_atomic_commit(state);
> > +
> > +out:
> > +	if (ret == -EDEADLK) {
> > +		drm_atomic_state_clear(state);
> > +		ret = drm_modeset_backoff(&ctx);
> > +		if (!ret)
> > +			goto retry;
> > +	}
> > +
> > +	drm_property_blob_put(damage);
> > +	kfree(rects);
> > +	drm_atomic_state_put(state);
> > +
> > +	drm_modeset_drop_locks(&ctx);
> > +	drm_modeset_acquire_fini(&ctx);
> > +
> > +	return ret;
> > +
> > +}
> > +EXPORT_SYMBOL(drm_atomic_helper_dirtyfb);
> > +
> >  /**
> >   * drm_atomic_helper_damage_iter_init - Initialize the damage iterator.
> >   * @iter: The iterator to initialize.
> > diff --git a/include/drm/drm_damage_helper.h b/include/drm/drm_damage_helper.h
> > index b9a0d05fb093..82a7128c9f97 100644
> > --- a/include/drm/drm_damage_helper.h
> > +++ b/include/drm/drm_damage_helper.h
> > @@ -67,6 +67,10 @@ struct drm_atomic_helper_damage_iter {
> >  void drm_plane_enable_fb_damage_clips(struct drm_plane *plane);
> >  void drm_atomic_helper_check_plane_damage(struct drm_atomic_state *state,
> >  					  struct drm_plane_state *plane_state);
> > +int drm_atomic_helper_dirtyfb(struct drm_framebuffer *fb,
> > +			      struct drm_file *file_priv, unsigned flags,
> > +			      unsigned color, struct drm_clip_rect *clips,
> > +			      unsigned num_clips);
> >  void
> >  drm_atomic_helper_damage_iter_init(struct drm_atomic_helper_damage_iter *iter,
> >  				   const struct drm_plane_state *old_state,
> > -- 
> > 2.17.1
> > 
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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