> -----Original Message-----
> From: Intel-gfx <intel-gfx-boun...@lists.freedesktop.org> On Behalf Of Ville
> Syrjala
> Sent: Wednesday, March 27, 2024 11:16 PM
> To: intel-gfx@lists.freedesktop.org
> Subject: [PATCH 02/13] drm/i915/cdclk: Fix voltage_level programming edge case
>
> From: Ville Syrjälä <ville.syrj...@linux.intel.com>
>
> Currently we only consider the relationship of the old and new CDCLK
> frequencies
> when determining whether to do the repgramming from
> intel_set_cdclk_pre_plane_update()
> or intel_set_cdclk_post_plane_update().
>
> It is technically possible to have a situation where the CDCLK frequency is
> decreasing, but the voltage_level is increasing due a DDI port. In this case
> we
> should bump the voltage level already in intel_set_cdclk_pre_plane_update()
> (so that the voltage_level will have been increased by the time the port gets
> enabled), while leaving the CDCLK frequency unchanged (as active planes/etc.
> may still depend on it).
> We can then reduce the CDCLK frequency to its final value from
> intel_set_cdclk_post_plane_update().
>
> In order to handle that correctly we shall construct a suitable amalgam of
> the old
> and new cdclk states in intel_set_cdclk_pre_plane_update().
>
> And we can simply call intel_set_cdclk() unconditionally in both places as it
> will
> not do anything if nothing actually changes vs. the current hw state.
>
> v2: Handle cdclk_state->disable_pipes
Looks Good to me.
Reviewed-by: Uma Shankar <uma.shan...@intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_cdclk.c | 27 +++++++++++++---------
> 1 file changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c
> b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index 619529dba095..504c5cbbcfff 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -2600,6 +2600,7 @@ intel_set_cdclk_pre_plane_update(struct
> intel_atomic_state *state)
> intel_atomic_get_old_cdclk_state(state);
> const struct intel_cdclk_state *new_cdclk_state =
> intel_atomic_get_new_cdclk_state(state);
> + struct intel_cdclk_config cdclk_config;
>
> if (!intel_cdclk_changed(&old_cdclk_state->actual,
> &new_cdclk_state->actual))
> @@ -2608,13 +2609,21 @@ intel_set_cdclk_pre_plane_update(struct
> intel_atomic_state *state)
> if (IS_DG2(i915))
> intel_cdclk_pcode_pre_notify(state);
>
> - if (new_cdclk_state->disable_pipes ||
> - old_cdclk_state->actual.cdclk <= new_cdclk_state->actual.cdclk) {
> - drm_WARN_ON(&i915->drm, !new_cdclk_state-
> >base.changed);
> + if (new_cdclk_state->disable_pipes) {
> + cdclk_config = new_cdclk_state->actual;
> + } else {
> + if (new_cdclk_state->actual.cdclk >= old_cdclk_state-
> >actual.cdclk)
> + cdclk_config = new_cdclk_state->actual;
> + else
> + cdclk_config = old_cdclk_state->actual;
>
> - intel_set_cdclk(i915, &new_cdclk_state->actual,
> - new_cdclk_state->pipe);
> + cdclk_config.voltage_level = max(new_cdclk_state-
> >actual.voltage_level,
> + old_cdclk_state-
> >actual.voltage_level);
> }
> +
> + drm_WARN_ON(&i915->drm, !new_cdclk_state->base.changed);
> +
> + intel_set_cdclk(i915, &cdclk_config, new_cdclk_state->pipe);
> }
>
> /**
> @@ -2640,13 +2649,9 @@ intel_set_cdclk_post_plane_update(struct
> intel_atomic_state *state)
> if (IS_DG2(i915))
> intel_cdclk_pcode_post_notify(state);
>
> - if (!new_cdclk_state->disable_pipes &&
> - old_cdclk_state->actual.cdclk > new_cdclk_state->actual.cdclk) {
> - drm_WARN_ON(&i915->drm, !new_cdclk_state-
> >base.changed);
> + drm_WARN_ON(&i915->drm, !new_cdclk_state->base.changed);
>
> - intel_set_cdclk(i915, &new_cdclk_state->actual,
> - new_cdclk_state->pipe);
> - }
> + intel_set_cdclk(i915, &new_cdclk_state->actual,
> +new_cdclk_state->pipe);
> }
>
> static int intel_pixel_rate_to_cdclk(const struct intel_crtc_state
> *crtc_state)
> --
> 2.43.2
