Am 08.11.21 um 21:55 schrieb Noralf Trønnes:
Den 01.11.2021 15.15, skrev Thomas Zimmermann: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 <tzimmerm...@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.+ 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
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