[PATCHv2 for 6.12 07/10] drm/amd/display: Adjust DCE 8-10 clock, don't overclock by 15%

Rosen Penev
2026-04-01T00:39:43Z

From: Timur Kristóf <timur.kristof@gmail.com>

[ Upstream commit 1ae45b5d4f371af8ae51a3827d0ec9fe27eeb867 ]

Adjust the nominal (and performance) clocks for DCE 8-10,
and set them to 625 MHz, which is the value used by the legacy
display code in amdgpu_atombios_get_clock_info.

This was tested with Hawaii, Tonga and Fiji.
These GPUs can output 4K 60Hz (10-bit depth) at 625 MHz.

The extra 15% clock was added as a workaround for a Polaris issue
which uses DCE 11, and should not have been used on DCE 8-10 which
are already hardcoded to the highest possible display clock.
Unfortunately, the extra 15% was mistakenly copied and kept
even on code paths which don't affect Polaris.

This commit fixes that and also adds a check to make sure
not to exceed the maximum DCE 8-10 display clock.

Fixes: 8cd61c313d8b ("drm/amd/display: Raise dispclk value for Polaris")
Fixes: dc88b4a684d2 ("drm/amd/display: make clk mgr soc specific")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Rodrigo Siqueira <siqueira@igalia.com>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
.../drm/amd/display/dc/clk_mgr/dce100/dce_clk_mgr.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dce100/dce_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dce100/dce_clk_mgr.c
index 5dbe89d9b72d..6131ede2db7a 100644
--- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dce100/dce_clk_mgr.c
+++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dce100/dce_clk_mgr.c
@@ -72,9 +72,9 @@ static const struct state_dependent_clocks dce80_max_clks_by_state[] = {
/* ClocksStateLow */
{ .display_clk_khz = 352000, .pixel_clk_khz = 330000},
/* ClocksStateNominal */
-{ .display_clk_khz = 600000, .pixel_clk_khz = 400000 },
+{ .display_clk_khz = 625000, .pixel_clk_khz = 400000 },
/* ClocksStatePerformance */
-{ .display_clk_khz = 600000, .pixel_clk_khz = 400000 } };
+{ .display_clk_khz = 625000, .pixel_clk_khz = 400000 } };

int dentist_get_divider_from_did(int did)
{
@@ -403,11 +403,9 @@ static void dce_update_clocks(struct clk_mgr *clk_mgr_base,
{
struct clk_mgr_internal *clk_mgr_dce = TO_CLK_MGR_INTERNAL(clk_mgr_base);
struct dm_pp_power_level_change_request level_change_req;
- int patched_disp_clk = context->bw_ctx.bw.dce.dispclk_khz;
-
- /*TODO: W/A for dal3 linux, investigate why this works */
- if (!clk_mgr_dce->dfs_bypass_active)
- patched_disp_clk = patched_disp_clk * 115 / 100;
+ const int max_disp_clk =
+ clk_mgr_dce->max_clks_by_state[DM_PP_CLOCKS_STATE_PERFORMANCE].display_clk_khz;
+ int patched_disp_clk = MIN(max_disp_clk, context->bw_ctx.bw.dce.dispclk_khz);

level_change_req.power_level = dce_get_required_clocks_state(clk_mgr_base, context);
/* get max clock state from PPLIB */
--
2.53.0