I believe I finally got the platform/panel that WA1183
was targeting.

WA 1183 aims to fix the cdclk change for
"CD clock frequency 308.57 or 617.14 MHz"

I faced one case here where the desired CDCLK to 308571 kHz,
VCO 8640000 kHz doesn't stick, unless that we unconditionally
disables and re-enables dpll0 and fully apply WA 1183.

[   42.857519] [drm:intel_dump_cdclk_state [i915]] Changing CDCLK to 308571 
kHz, VCO 8640000 kHz, ref 24000 kHz, bypass 24000 kHz, voltage level 0
[   42.897269] cdclk state doesn't match!
[   42.901052] WARNING: CPU: 5 PID: 1116 at 
drivers/gpu/drm/i915/intel_cdclk.c:2084 intel_set_cdclk+0x5d/0x110 [i915]
[   42.938004] RIP: 0010:intel_set_cdclk+0x5d/0x110 [i915]
[   43.155253] WARNING: CPU: 5 PID: 1116 at 
drivers/gpu/drm/i915/intel_cdclk.c:2084 intel_set_cdclk+0x5d/0x110 [i915]
[   43.170277] [drm:intel_dump_cdclk_state [i915]] [hw state] 337500 kHz, VCO 
8100000 kHz, ref 24000 kHz, bypass 24000 kHz, voltage level 0
[   43.182566] [drm:intel_dump_cdclk_state [i915]] [sw state] 308571 kHz, VCO 
8640000 kHz, ref 24000 kHz, bypass 24000 kHz, voltage level 0

Fixes: 53421c2fe99c ("drm/i915: Apply Display WA #1183 on skl, kbl, and cfl")
Cc: Arthur J Runyan" <[email protected]>
Cc: Lucas De Marchi <[email protected]>
Cc: Ville Syrjälä <[email protected]>
Signed-off-by: Rodrigo Vivi <[email protected]>
---
 drivers/gpu/drm/i915/intel_cdclk.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_cdclk.c 
b/drivers/gpu/drm/i915/intel_cdclk.c
index 32d24c69da3c..5a65a79965cd 100644
--- a/drivers/gpu/drm/i915/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/intel_cdclk.c
@@ -1026,26 +1026,21 @@ static void skl_set_cdclk(struct drm_i915_private 
*dev_priv,
                break;
        }
 
-       if (dev_priv->cdclk.hw.vco != 0 &&
-           dev_priv->cdclk.hw.vco != vco)
-               skl_dpll0_disable(dev_priv);
+       skl_dpll0_disable(dev_priv);
 
        cdclk_ctl = I915_READ(CDCLK_CTL);
 
-       if (dev_priv->cdclk.hw.vco != vco) {
-               /* Wa Display #1183: skl,kbl,cfl */
-               cdclk_ctl &= ~(CDCLK_FREQ_SEL_MASK | CDCLK_FREQ_DECIMAL_MASK);
-               cdclk_ctl |= freq_select | skl_cdclk_decimal(cdclk);
-               I915_WRITE(CDCLK_CTL, cdclk_ctl);
-       }
+       /* Wa Display #1183: skl,kbl,cfl */
+       cdclk_ctl &= ~(CDCLK_FREQ_SEL_MASK | CDCLK_FREQ_DECIMAL_MASK);
+       cdclk_ctl |= freq_select | skl_cdclk_decimal(cdclk);
+       I915_WRITE(CDCLK_CTL, cdclk_ctl);
 
        /* Wa Display #1183: skl,kbl,cfl */
        cdclk_ctl |= CDCLK_DIVMUX_CD_OVERRIDE;
        I915_WRITE(CDCLK_CTL, cdclk_ctl);
        POSTING_READ(CDCLK_CTL);
 
-       if (dev_priv->cdclk.hw.vco != vco)
-               skl_dpll0_enable(dev_priv, vco);
+       skl_dpll0_enable(dev_priv, vco);
 
        /* Wa Display #1183: skl,kbl,cfl */
        cdclk_ctl &= ~(CDCLK_FREQ_SEL_MASK | CDCLK_FREQ_DECIMAL_MASK);
-- 
2.13.6

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