[Intel-gfx] [PATCH 16/18] drm/i915/skl: Do not disable cdclk PLL if csr firmware is present.

[Animesh Manna]

While display engine entering into low power state no need to disable
cdclk pll as CSR firmware of dmc will take care. If pll is already
enabled firmware execution sequence will be blocked. This is one
of the criteria for dmc to work properly.

Cc: Damien Lespiau <damien.lespiau at intel.com>
Cc: Imre Deak <imre.deak at intel.com>
Cc: Sunil Kamath <sunil.kamath at intel.com>
Signed-off-by: Animesh Manna <animesh.manna at intel.com>
Signed-off-bt: Vathsala Nagaraju <vathsala.nagaraju at intel.com>
Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index af0bcfe..ef2ef4d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5675,10 +5675,13 @@ void skl_uninit_cdclk(struct drm_i915_private *dev_priv)
 	if (I915_READ(DBUF_CTL) & DBUF_POWER_STATE)
 		DRM_ERROR("DBuf power disable timeout\n");
 
-	/* disable DPLL0 */
-	I915_WRITE(LCPLL1_CTL, I915_READ(LCPLL1_CTL) & ~LCPLL_PLL_ENABLE);
-	if (wait_for(!(I915_READ(LCPLL1_CTL) & LCPLL_PLL_LOCK), 1))
-		DRM_ERROR("Couldn't disable DPLL0\n");
+	if (dev_priv->csr.dmc_payload) {
+		/* disable DPLL0 */
+		I915_WRITE(LCPLL1_CTL, I915_READ(LCPLL1_CTL) &
+					~LCPLL_PLL_ENABLE);
+		if (wait_for(!(I915_READ(LCPLL1_CTL) & LCPLL_PLL_LOCK), 1))
+			DRM_ERROR("Couldn't disable DPLL0\n");
+	}
 
 	intel_display_power_put(dev_priv, POWER_DOMAIN_PLLS);
 }
-- 
2.0.2