On Tue, 14 Nov 2023 17:05:12 +0100 Javier Martinez Canillas javierm@redhat.com wrote:
Thomas Zimmermann tzimmermann@suse.de writes:
Hi
Am 09.11.23 um 18:24 schrieb Javier Martinez Canillas:
[...]
struct drm_rect src; memset(iter, 0, sizeof(*iter)); @@ -223,7 +224,8 @@ __drm_atomic_helper_damage_iter_init(struct drm_atomic_helper_damage_iter *iter, iter->plane_src.x2 = (src.x2 >> 16) + !!(src.x2 & 0xFFFF); iter->plane_src.y2 = (src.y2 >> 16) + !!(src.y2 & 0xFFFF);
- if (!iter->clips || !drm_rect_equals(&state->src, &old_state->src)) {
- if (!iter->clips || !drm_rect_equals(&state->src, &old_state->src) ||
(buffer_damage && old_state->fb != state->fb)) {I'd assume that this change effectivly disables damage handling. AFAICT user space often does a page flip with a new framebuffer plus damage data. Now, with each change of the framebuffer we ignore the damage information. It's not a blocker as that's the behavior before 6.4, but we should be aware of it.
Yes, which is the goal of this patch since page flip with a new framebuffer attached to a plane plus damage information can't be supported by drivers that do per-buffer uploads.
This was causing some weston and wlroots to have flickering artifacts, due the framebuffers being changed since the last plane update.
For now it was decided with Sima, Simon and Pekka that is the best we can do and the reason why I add a TODO in patch #6.
Hi all,
this made me thinking...
The per-buffer damage accumulation that would be needed is per upload-buffer, not per KMS FB from userspace. So it should not make any difference whether userspace flips to another FB or not, the damage will need to be accumulated per upload-buffer anyway if the driver is flipping upload-buffers, in order to make the upload-buffer fully up-to-date.
Why was that not more broken than it already was?
Is there a fixed 1:1 relationship between userspace KMS FBs and the driver upload-buffers?
Userspace is already taking care that the KMS FB is always fully up-to-date, FWIW, so the kernel can certainly read areas outside of FB_DAMAGE_CLIPS if it wants to.
Thanks, pq