[PATCH 6.8 002/158] drm/i915/cdclk: Fix voltage_level programming edge case

Greg Kroah-Hartman
2024-04-23T21:40:59Z

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

[ Upstream commit 6154cc9177ccea00c89ce0bf93352e474b819ff2 ]

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
v3: Only synchronize the cd2x update against the pipe's vblank
when the cdclk frequency is changing during the current
commit phase (Gustavo)

Cc: stable@vger.kernel.org
Cc: Gustavo Sousa <gustavo.sousa@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240402155016.13733-3-ville.syrjala@linux.intel.com
(cherry picked from commit 34d127e2bdef73a923aa0dcd95cbc3257ad5af52)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/i915/display/intel_cdclk.c | 37 ++++++++++++++++------
1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
index 6e36a15284537..7ba30d26f620c 100644
--- a/drivers/gpu/drm/i915/display/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
@@ -2512,7 +2512,8 @@ 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);
- enum pipe pipe = new_cdclk_state->pipe;
+ struct intel_cdclk_config cdclk_config;
+ enum pipe pipe;

if (!intel_cdclk_changed(&old_cdclk_state->actual,
&new_cdclk_state->actual))
@@ -2521,12 +2522,25 @@ 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;
+ pipe = INVALID_PIPE;
+ } else {
+ if (new_cdclk_state->actual.cdclk >= old_cdclk_state->actual.cdclk) {
+ cdclk_config = new_cdclk_state->actual;
+ pipe = new_cdclk_state->pipe;
+ } else {
+ cdclk_config = old_cdclk_state->actual;
+ pipe = INVALID_PIPE;
+ }

- intel_set_cdclk(i915, &new_cdclk_state->actual, 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, pipe);
}

/**
@@ -2544,7 +2558,7 @@ intel_set_cdclk_post_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);
- enum pipe pipe = new_cdclk_state->pipe;
+ enum pipe pipe;

if (!intel_cdclk_changed(&old_cdclk_state->actual,
&new_cdclk_state->actual))
@@ -2554,11 +2568,14 @@ intel_set_cdclk_post_plane_update(struct intel_atomic_state *state)
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);
+ new_cdclk_state->actual.cdclk < old_cdclk_state->actual.cdclk)
+ pipe = new_cdclk_state->pipe;
+ else
+ pipe = INVALID_PIPE;

- intel_set_cdclk(i915, &new_cdclk_state->actual, pipe);
- }
+ drm_WARN_ON(&i915->drm, !new_cdclk_state->base.changed);
+
+ intel_set_cdclk(i915, &new_cdclk_state->actual, pipe);
}

static int intel_pixel_rate_to_cdclk(const struct intel_crtc_state *crtc_state)
--
2.43.0