Am 08.11.21 um 21:55 schrieb Noralf Trønnes:

Den 01.11.2021 15.15, skrev Thomas Zimmermann:

quoted

Enable the FB_DAMAGE_CLIPS property to reduce display-update
overhead. Also fixes a warning in the kernel log.

   simple-framebuffer simple-framebuffer.0: [drm] drm_plane_enable_fb_damage_clips() not called

Fix the computation of the blit rectangle. This wasn't an issue so
far, as simpledrm always blitted the full framebuffer. The code now
supports damage clipping and virtual screen sizes.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
  drivers/gpu/drm/tiny/simpledrm.c | 30 ++++++++++++++++++++++--------
  1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index 571f716ff427..e872121e9fb0 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c

@@ -642,7 +642,7 @@ simpledrm_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
  	void *vmap = shadow_plane_state->data[0].vaddr; /* TODO: Use mapping abstraction */
  	struct drm_device *dev = &sdev->dev;
  	void __iomem *dst = sdev->screen_base;
-	struct drm_rect clip;
+	struct drm_rect src_clip, dst_clip;
  	int idx;
  
  	if (!fb)

@@ -651,10 +651,14 @@ simpledrm_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
  	if (!drm_dev_enter(dev, &idx))
  		return;
  
-	drm_rect_init(&clip, 0, 0, fb->width, fb->height);
+	drm_rect_fp_to_int(&src_clip, &plane_state->src);
  
-	dst += drm_fb_clip_offset(sdev->pitch, sdev->format, &clip);
-	drm_fb_blit_toio(dst, sdev->pitch, sdev->format->format, vmap, fb, &clip);
+	dst_clip = plane_state->dst;

I assume that src_clip and dst_clip are of the same size, since scaling
is not supported. What prevents dst_clip from being bigger than the
buffer that's being blitted into? Where is that bounds checking done?

The value of dst_clip comes from plane_state->dst, which gets 
initialized in drm_atomic_helper_check_plane_state(). [1] The fields are 
taken from the crtc_{x,y,w,h} values by drm_plane_get_dest(). [2] For 
primary planes, the crtc_{x,y,w,h} values are initialized in 
__drm_atomic_helper_set_config() to the size of the display. [3] That 
size comes directly from the current video mode. [4] From all I can see 
this cannot overflow.

Best regards
Thomas

[1] 
https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/drm_atomic_helper.c#L807
[2] 
https://elixir.bootlin.com/linux/latest/source/include/drm/drm_plane.h#L257
[3] 
https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/drm_atomic.c#L1590
[4] 
https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/drm_modes.c#L788

Noralf.

quoted

+	if (!drm_rect_intersect(&dst_clip, &src_clip))
+		return;
+
+	dst += drm_fb_clip_offset(sdev->pitch, sdev->format, &dst_clip);
+	drm_fb_blit_toio(dst, sdev->pitch, sdev->format->format, vmap, fb, &src_clip);
  
  	drm_dev_exit(idx);
  }

@@ -686,20 +690,28 @@ simpledrm_simple_display_pipe_update(struct drm_simple_display_pipe *pipe,
  	struct drm_framebuffer *fb = plane_state->fb;
  	struct drm_device *dev = &sdev->dev;
  	void __iomem *dst = sdev->screen_base;
-	struct drm_rect clip;
+	struct drm_rect damage_clip, src_clip, dst_clip;
  	int idx;
  
  	if (!fb)
  		return;
  
-	if (!drm_atomic_helper_damage_merged(old_plane_state, plane_state, &clip))
+	if (!drm_atomic_helper_damage_merged(old_plane_state, plane_state, &damage_clip))
+		return;
+
+	drm_rect_fp_to_int(&src_clip, &plane_state->src);
+	if (!drm_rect_intersect(&src_clip, &damage_clip))
+		return;
+
+	dst_clip = plane_state->dst;
+	if (!drm_rect_intersect(&dst_clip, &src_clip))
  		return;
  
  	if (!drm_dev_enter(dev, &idx))
  		return;
  
-	dst += drm_fb_clip_offset(sdev->pitch, sdev->format, &clip);
-	drm_fb_blit_toio(dst, sdev->pitch, sdev->format->format, vmap, fb, &clip);
+	dst += drm_fb_clip_offset(sdev->pitch, sdev->format, &dst_clip);
+	drm_fb_blit_toio(dst, sdev->pitch, sdev->format->format, vmap, fb, &src_clip);
  
  	drm_dev_exit(idx);
  }

@@ -794,6 +806,8 @@ static int simpledrm_device_init_modeset(struct simpledrm_device *sdev)
  	if (ret)
  		return ret;
  
+	drm_plane_enable_fb_damage_clips(&pipe->plane);
+
  	drm_mode_config_reset(dev);
  
  	return 0;

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