OpenHarmony/third_party_mesa3d
2
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

freedreno: Describe LRZ feedback mechanism

Browse Source 
Some draws do write depth but cannot contribute to LRZ during the BINNING pass
e.g. when fragment shader has "discard" in it, however they can contribute to
LRZ during the RENDERING pass via LRZ feedback meachanism. This may allow the
draws that follow to depth test against the updated LRZ, this is especially
important if such "bad" draws were at the start of the renderpass.

LRZ feedback happens during the RENDERING pass when LRZ_FEEDBACK_ZMODE_MASK
is set, if draw has a6xx_ztest_mode that has corresponding flag set in
LRZ_FEEDBACK_ZMODE_MASK - its depth values would be used for feedback.

LRZ feedback alongside with LRZ testing also works during sysmem rendering.

Signed-off-by: Danylo Piliaiev <dpiliaiev@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25345>
This commit is contained in:
Danylo Piliaiev
2023-09-20 16:45:37 +02:00
committed by Marge Bot
parent 78c5daf029
commit 229bd7b9b9
7 changed files with 60 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
docs/drivers/freedreno/hw/lrz.rst
View File

@@ -95,6 +95,21 @@ This way it's always valid to fast-clear.
On A7XX, the original depth clear value can be specified exactly allowing for
fast-clear to any value rather than just ``1.0`` or ``0.0``.
LRZ Feedback
-------------
Some draws do write depth but cannot contribute to LRZ during the BINNING pass
e.g. when fragment shader has "discard" in it, however they can contribute to LRZ
during the RENDERING pass via LRZ feedback mechanism. This may allow the draws
that follow to depth test against the updated LRZ, this is especially important
if such "bad" draws were at the start of the renderpass.
LRZ feedback happens during the RENDERING pass when ``LRZ_FEEDBACK_ZMODE_MASK``
is set, if draw has a6xx_ztest_mode that has corresponding flag set in
``LRZ_FEEDBACK_ZMODE_MASK`` - its depth values would be used for feedback.
LRZ feedback alongside with LRZ testing also works during sysmem rendering.
LRZ Precision
-------------