On Thursday, November 16th, 2023 at 13:06, Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:
+ * Note that there are two types of damage handling: frame damage and buffer
+ * damage. The type of damage handling implemented depends on a driver's upload
+ * target. Drivers implementing a per-plane or per-CRTC upload target need to
+ * handle frame damage while drivers implementing a per-buffer upload target
+ * need to handle buffer damage.
+ *
+ * The existing damage helpers only support the frame damage type, there is no
+ * buffer age support or similar damage accumulation algorithm implemented yet.
+ *
+ * Only drivers handling frame damage can use the mentiored damage helpers to
Typo: mentioned
+ * iterate over the damaged regions. Drivers that handle buffer damage, need to
+ * set &struct drm_plane_state.ignore_damage_clips as an indication to
+ * drm_atomic_helper_damage_iter_init() that the damage clips should be ignored.
+ * In that case, the returned damage rectangle is the &drm_plane_state.src since
+ * a full plane update should happen.
+ *
+ * For more information about the two type of damage, see:
+ * https://registry.khronos.org/EGL/extensions/KHR/EGL_KHR_swap_buffers_with_damage.txt
+ * https://emersion.fr/blog/2019/intro-to-damage-tracking/
One thought you might want to consider.
These URLs are helpful. The only issue I have is that frame damage and
buffer damage are user-space concepts. The kernel bug is that damage
handling expects the backing storage/upload buffer not to change for a
given plane. If the upload buffer changes between page flips, the new
upload buffer has to be updated as a whole. Hence no damage handling then.
Why would these concepts be specific to user-space? The kernel could
better handle buffer damage instead of forcing full damage, by doing
something similar to what user-space does.
Anyways:
Reviewed-by: Simon Ser <contact@xxxxxxxxxxx>
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