[PATCH 1/4] drm/i915/xe2lpd: Update bxt_sanitize_cdclk()

[Gustavo Sousa]

With Xe2_LPD, there were changes to the way CDCLK_CTL must be
programmed. Those were reflected on _bxt_set_cdclk() with commit
3d3696c0fed1 ("drm/i915/lnl: Start using CDCLK through PLL"), but
bxt_sanitize_cdclk() was left out.

This was causing some issues when loading the driver with a pre-existing
active display configuration: the driver would mistakenly take the
current value of CDCLK_CTL as wrong and the sanitization would be
triggered.

In a scenario where the display was already configured with a high
CDCLKC and had plane(s) enabled, FIFO underrun errors were reported,
because the current sanitization code selects the minimum possible
CDCLK.

Fix that by updating bxt_sanitize_cdclk() to match the changes made in
_bxt_set_cdclk(). Ideally, we would have a common function to derive the
value for CDCLK_CTL, but that can be done in a future change.

Signed-off-by: Gustavo Sousa <gustavo.sousa at intel.com>
---
 drivers/gpu/drm/i915/display/intel_cdclk.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
index c5fecde7afa8..0012e3171f3f 100644
--- a/drivers/gpu/drm/i915/display/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
@@ -2071,7 +2071,10 @@ static void bxt_sanitize_cdclk(struct drm_i915_private *dev_priv)
 	if (vco != dev_priv->display.cdclk.hw.vco)
 		goto sanitize;
 
-	expected = skl_cdclk_decimal(cdclk);
+	if (DISPLAY_VER(dev_priv) >= 20)
+		expected = MDCLK_SOURCE_SEL_CDCLK_PLL;
+	else
+		expected = skl_cdclk_decimal(cdclk);
 
 	/* Figure out what CD2X divider we should be using for this cdclk */
 	if (HAS_CDCLK_SQUASH(dev_priv))
-- 
2.43.0