linux_dsm_epyc7002/drivers/gpu
Krunoslav Kovac e752058b86 drm/amd/display: Optimize gamma calculations
[Why&How]

1. Stack usage is pretty high as fixed31_32 struct is 8 bytes and we
have functions with >30 vars on the stack.

2. Optimize gamma calculation by reducing number of calls to
dc_fixpt_pow Our X points are divided into 32 regions wth 16 pts each.
Each region is 2x the previous, meaning x[i] = 2*x[i-16] for i>=16.
Using (2x)^gamma = 2^gamma * x^gamma, we can recursively compute powers
of gamma, we just need first 16 pts to start it up. dc_fixpt_pow() is
expensive, it computes x^y by doing exp(y*logx) Exp is done by Taylor
series approximation, and log by Newton-like approximation that also
uses exp internally. In short, it's significantly heavier than
run-of-the-mill addition/subtraction/multiply.

Signed-off-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
2019-07-18 14:27:25 -05:00
..
drm drm/amd/display: Optimize gamma calculations 2019-07-18 14:27:25 -05:00
host1x drm/tegra: Changes for v5.3-rc1 2019-06-25 12:59:43 +10:00
ipu-v3 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 288 2019-06-05 17:36:37 +02:00
vga Merge branch 'topic/remove-fbcon-notifiers' into drm-misc-next 2019-06-19 12:33:05 +02:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00