[Intel-gfx] [PATCH] drm/i915: Apply Wa Display #1183 on skl, kbl, and cfl.

Fri Oct 20 22:15:49 UTC 2017

Wa Display #1183 was recently added to workaround
"Failures when enabling DPLL0 with eDP link rate 2.16
or 4.32 GHz and CD clock frequency 308.57 or 617.14 MHz
(CDCLK_CTL CD Frequency Select 10b or 11b) used in this
 enabling or in previous enabling."

This Workaround was designed to minimize the impact only
to save the bad case with that link rates. But HW engineers
indicated that it should be safe to apply broadly. Although
they were expecting the DPLL0 link rate to be unchanged on
runtime.

So, we could only apply if vco is 8640000. However this
would require a synchronization with intel_csr.c. Probably
a dev_priv->wa1183 bool.

Another equaly ugly possibility would be to save the edp_link_rate
on dev_priv. With this we could fix one corner case that
although rare I believe our code could hit that is if
desired port clock is 4.32GHz our dpll0_enable initially
sets the link rate to DPLL_CTRL1_LINK_RATE_1080 while
it should set to DPLL_CTRL1_LINK_RATE_2160.

v2: - Avoid RMW for every step since we know exactly what
      we should set. This also fix a bug on v1.
    - Remove set of minimal CDCLK since this is not needed
      in the WA. At least one less write to CDCLK_CTL
      since the other ones cannot be grouped.
    - Fix commit message.

Cc: Arthur J Runyan <arthur.j.runyan at intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h         |  2 ++
 drivers/gpu/drm/i915/intel_cdclk.c      | 37 ++++++++++++++++++++++-----------
 drivers/gpu/drm/i915/intel_runtime_pm.c | 10 +++++++++
 3 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 68a58cce6ab1..816b9665e092 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -6980,6 +6980,7 @@ enum {
 #define  RESET_PCH_HANDSHAKE_ENABLE	(1<<4)
 
 #define GEN8_CHICKEN_DCPR_1		_MMIO(0x46430)
+#define   SKL_SELECT_ALTERNATE_DC_EXIT	(1<<30)
 #define   MASK_WAKEMEM			(1<<13)
 
 #define SKL_DFSM			_MMIO(0x51000)
@@ -8526,6 +8527,7 @@ enum skl_power_gate {
 #define  BXT_CDCLK_CD2X_DIV_SEL_4	(3<<22)
 #define  BXT_CDCLK_CD2X_PIPE(pipe)	((pipe)<<20)
 #define  BXT_CDCLK_CD2X_PIPE_NONE	BXT_CDCLK_CD2X_PIPE(3)
+#define  DIVMUX_CD_OVERRIDE		(1<<19)
 #define  BXT_CDCLK_SSA_PRECHARGE_ENABLE	(1<<16)
 #define  CDCLK_FREQ_DECIMAL_MASK	(0x7ff)
 
diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c
index b2a6d62b71c0..5ecd5cb44e43 100644
--- a/drivers/gpu/drm/i915/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/intel_cdclk.c
@@ -858,18 +858,13 @@ static void skl_set_preferred_cdclk_vco(struct drm_i915_private *dev_priv,
 		intel_update_max_cdclk(dev_priv);
 }
 
-static void skl_dpll0_enable(struct drm_i915_private *dev_priv, int vco)
+static void skl_dpll0_enable(struct drm_i915_private *dev_priv, int vco,
+			     u32 freq_select)
 {
-	int min_cdclk = skl_calc_cdclk(0, vco);
 	u32 val;
 
 	WARN_ON(vco != 8100000 && vco != 8640000);
 
-	/* select the minimum CDCLK before enabling DPLL 0 */
-	val = CDCLK_FREQ_337_308 | skl_cdclk_decimal(min_cdclk);
-	I915_WRITE(CDCLK_CTL, val);
-	POSTING_READ(CDCLK_CTL);
-
 	/*
 	 * We always enable DPLL0 with the lowest link rate possible, but still
 	 * taking into account the VCO required to operate the eDP panel at the
@@ -894,6 +889,10 @@ static void skl_dpll0_enable(struct drm_i915_private *dev_priv, int vco)
 	I915_WRITE(DPLL_CTRL1, val);
 	POSTING_READ(DPLL_CTRL1);
 
+	/* Wa Display #1183: skl,kbl,cfl */
+	val = DIVMUX_CD_OVERRIDE;
+	I915_WRITE(CDCLK_CTL, val);
+
 	I915_WRITE(LCPLL1_CTL, I915_READ(LCPLL1_CTL) | LCPLL_PLL_ENABLE);
 
 	if (intel_wait_for_register(dev_priv,
@@ -901,6 +900,17 @@ static void skl_dpll0_enable(struct drm_i915_private *dev_priv, int vco)
 				    5))
 		DRM_ERROR("DPLL0 not locked\n");
 
+	/* Wa Display #1183: skl,kbl,cfl */
+	val &= ~CDCLK_FREQ_SEL_MASK;;
+	I915_WRITE(CDCLK_CTL, val);
+
+	val |= freq_select;
+	I915_WRITE(CDCLK_CTL, val);
+
+	/* Wa Display #1183: skl,kbl,cfl */
+	val &= ~DIVMUX_CD_OVERRIDE;
+	I915_WRITE(CDCLK_CTL, val);
+
 	dev_priv->cdclk.hw.vco = vco;
 
 	/* We'll want to keep using the current vco from now on. */
@@ -964,15 +974,18 @@ static void skl_set_cdclk(struct drm_i915_private *dev_priv,
 		break;
 	}
 
+	freq_select |= skl_cdclk_decimal(cdclk);
+
 	if (dev_priv->cdclk.hw.vco != 0 &&
 	    dev_priv->cdclk.hw.vco != vco)
 		skl_dpll0_disable(dev_priv);
 
-	if (dev_priv->cdclk.hw.vco != vco)
-		skl_dpll0_enable(dev_priv, vco);
-
-	I915_WRITE(CDCLK_CTL, freq_select | skl_cdclk_decimal(cdclk));
-	POSTING_READ(CDCLK_CTL);
+	if (dev_priv->cdclk.hw.vco != vco) {
+		skl_dpll0_enable(dev_priv, vco, freq_select);
+	} else {
+		I915_WRITE(CDCLK_CTL, freq_select);
+		POSTING_READ(CDCLK_CTL);
+	}
 
 	/* inform PCU of the change */
 	mutex_lock(&dev_priv->pcu_lock);
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 8af286c63d3b..e0bc2debdad0 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -598,6 +598,11 @@ void gen9_enable_dc5(struct drm_i915_private *dev_priv)
 
 	DRM_DEBUG_KMS("Enabling DC5\n");
 
+	/* Wa Display #1183: skl,kbl,cfl */
+	if (IS_GEN9_BC(dev_priv))
+		I915_WRITE(GEN8_CHICKEN_DCPR_1, I915_READ(GEN8_CHICKEN_DCPR_1) |
+			   SKL_SELECT_ALTERNATE_DC_EXIT);
+
 	gen9_set_dc_state(dev_priv, DC_STATE_EN_UPTO_DC5);
 }
 
@@ -625,6 +630,11 @@ void skl_disable_dc6(struct drm_i915_private *dev_priv)
 {
 	DRM_DEBUG_KMS("Disabling DC6\n");
 
+	/* Wa Display #1183: skl,kbl,cfl */
+	if (IS_GEN9_BC(dev_priv))
+		I915_WRITE(GEN8_CHICKEN_DCPR_1, I915_READ(GEN8_CHICKEN_DCPR_1) |
+			   SKL_SELECT_ALTERNATE_DC_EXIT);
+
 	gen9_set_dc_state(dev_priv, DC_STATE_DISABLE);
 }
 
-- 
2.13.5

