[PATCH 2/4] drm/i915: Use old mbus_join value when increasing CDCLK

[Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>]

In order to make sure we are not breaking the proper sequence
lets to updates step by step and don't change MBUS join value
during MDCLK/CDCLK programming stage.
MBUS join programming would be taken care by pre/post ddb hooks.

v2: - Reworded comment about using old mbus_join value in
      intel_set_cdclk(Ville Syrjälä)

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
---
 drivers/gpu/drm/i915/display/intel_cdclk.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
index 31aaa9780dfcf..c7813d433c424 100644
--- a/drivers/gpu/drm/i915/display/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
@@ -2611,9 +2611,19 @@ intel_set_cdclk_pre_plane_update(struct intel_atomic_state *state)
 
 	if (pipe == INVALID_PIPE ||
 	    old_cdclk_state->actual.cdclk <= new_cdclk_state->actual.cdclk) {
+		struct intel_cdclk_config cdclk_config;
+
 		drm_WARN_ON(&i915->drm, !new_cdclk_state->base.changed);
 
-		intel_set_cdclk(i915, &new_cdclk_state->actual, pipe);
+		/*
+		 * By this hack we want to prevent mbus_join to be changed
+		 * beforehand - we will take care of this later in
+		 * intel_dbuf_mbus_post_ddb_update
+		 */
+		cdclk_config = new_cdclk_state->actual;
+		cdclk_config.joined_mbus = old_cdclk_state->actual.joined_mbus;
+
+		intel_set_cdclk(i915, &cdclk_config, pipe);
 	}
 }
 
-- 
2.37.3