kernel/linux.git/drivers/gpu/drm/amd/amdgpu/amdgpu_pll.h, branch v6.12.80Linux kernel stable tree (mirror)https://git.radix-linux.su/kernel/linux.git/atom?h=v6.12.802021-08-24T19:35:25+00:00drm/amdgpu/OLAND: clip the ref divider max value2021-08-24T19:35:25+00:00Shashank Sharmashashank.sharma@amd.com2021-08-20T04:50:02+00:00urn:sha1:7301757ea1fbead24f7c5687f828940a698a95db
This patch limits the ref_div_max value to 100, during the
calculation of PLL feedback reference divider. With current
value (128), the produced fb_ref_div value generates unstable
output at particular frequencies. Radeon driver limits this
value at 100.
On Oland, when we try to setup mode 2048x1280@60 (a bit weird,
I know), it demands a clock of 221270 Khz. It's been observed
that the PLL calculations using values 128 and 100 are vastly
different, and look like this:
+------------------------------------------+
|Parameter |AMDGPU |Radeon |
| | | |
+-------------+----------------------------+
|Clock feedback | |
|divider max | 128 | 100 |
|cap value | | |
| | | |
| | | |
+------------------------------------------+
|ref_div_max | | |
| | 42 | 20 |
| | | |
| | | |
+------------------------------------------+
|ref_div | 42 | 20 |
| | | |
+------------------------------------------+
|fb_div | 10326 | 8195 |
+------------------------------------------+
|fb_div | 1024 | 163 |
+------------------------------------------+
|fb_dev_p | 4 | 9 |
|frac fb_de^_p| | |
+----------------------------+-------------+
With ref_div_max value clipped at 100, AMDGPU driver can also
drive videmode 2048x1280@60 (221Mhz) and produce proper output
without any blanking and distortion on the screen.
PS: This value was changed from 128 to 100 in Radeon driver also, here:
https://github.com/freedesktop/drm-tip/commit/4b21ce1b4b5d262e7d4656b8ececc891fc3cb806
V1:
Got acks from:
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
V2:
- Restricting the changes only for OLAND, just to avoid any regression
for other cards.
- Changed unsigned -> unsigned int to make checkpatch quiet.
V3: Apply the change on SI family (not only oland) (Christian)
Cc: Alex Deucher <Alexander.Deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Eddy Qin <Eddy.Qin@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
drm/amdgpu: add core driver (v4)2015-06-04T01:03:15+00:00Alex Deucheralexander.deucher@amd.com2015-04-20T20:55:21+00:00urn:sha1:d38ceaf99ed015f2a0b9af3499791bd3a3daae21
This adds the non-asic specific core driver code.
v2: remove extra kconfig option
v3: implement minor fixes from Fengguang Wu
v4: fix cast in amdgpu_ucode.c
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Jammy Zhou <Jammy.Zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>