[PATCH 2/7] drm/amd/display: Adjust DCE 8-10 clock, don't overclock by 15%

[Alex Deucher]

On Mon, Aug 4, 2025 at 12:35 PM Timur Kristóf <timur.kristof at gmail.com> wrote:
>
> On Mon, 2025-08-04 at 11:56 -0400, Alex Deucher wrote:
> > On Thu, Jul 31, 2025 at 5:58 AM Timur Kristóf
> > <timur.kristof at gmail.com> wrote:
> > >
> > > 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 at gmail.com>
> > >
> > > x
> >
> > Stray x here.  with that fixed:
> > Acked-by: Alex Deucher <alexander.deucher at amd.com>
>
> Thanks!
> Sorry about that, that's a typo that I made during a rebase.
>
> Maybe a silly question but what is the right way to deal with it?
> Should I send the entire series or just the patch with the typo fixed?
> Or can you just delete the typo when you are applying it to your tree?

If you end up resending the series, you can fix it then.  If not, I
can fix it up when I apply the patches.  I wanted to give it a few
more days so the display guys have a chance to review them.

Alex

>
> Timur
>
> >
> > > ---
> > >  .../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 26feefbb8990..69e9540f553b 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)
> > >  {
> > > @@ -400,11 +400,9 @@ 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 */
> > > --
> > > 2.50.1
> > >