Re: [PATCH v2 4/5] drm/plane: Extend damage tracking kernel-doc

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi

Am 16.11.23 um 16:24 schrieb Pekka Paalanen:
On Thu, 16 Nov 2023 13:34:07 +0100
Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:

Hi

Am 16.11.23 um 13:14 schrieb Simon Ser:
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.

The terms 'frame damage' and 'buffer damage' do not exist in the kernel.
The problem can be better described in wording that is common within the
context of the kernel drivers.

What terms does the kernel use for these two different concepts of
damage?

None AFAIK. Damage is relative to the plane's backing storage/upload buffer. That's frame damage. We never needed a name for buffer damage as we don't support it.

Best regards
Thomas



Thanks,
pq

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

Attachment: OpenPGP_signature.asc
Description: OpenPGP digital signature


[Index of Archives]     [Linux DRI Users]     [Linux Intel Graphics]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux