[Intel-gfx] [PATCH] HAX drm/i915: Move init_clock_gating() back to where it was

[Chris Wilson]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Apparently setting up a bunch of GT registers before we've properly
initialized the rest of the GT hardware leads to these setting being
lost. So looks like I broke HSW with commit b7048ea12fbb ("drm/i915:
Do .init_clock_gating() earlier to avoid it clobbering watermarks")
by doing init_clock_gating() too early. This should actually affect
other platforms as well, but apparently not to such a great degree.

What I was ultimately after in that commit was to move the
ilk_init_lp_watermarks() call earlier. So let's undo the damage and
move init_clock_gating() back to where it was, and call
ilk_init_lp_watermarks() just before the watermark state readout.

This highlights how fragile and messed up our init order really is.
I wonder why we even initialize the display before gem. The opposite
order would make much more sense to me...

REVERT THE REVERT, just do the ilk_init_lp_watermarks() motion.
---
 drivers/gpu/drm/i915/intel_display.c |  1 +
 drivers/gpu/drm/i915/intel_pm.c      | 40 ++++++++++++++++--------------------
 2 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 737de251d0f8..bd198bd3e10d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3676,6 +3676,7 @@ void intel_finish_reset(struct drm_i915_private *dev_priv)
 
 		intel_pps_unlock_regs_wa(dev_priv);
 		intel_modeset_init_hw(dev);
+		intel_init_clock_gating(dev_priv);
 
 		spin_lock_irq(&dev_priv->irq_lock);
 		if (dev_priv->display.hpd_irq_setup)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 07118c0b69d3..352a6739ed70 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5754,12 +5754,30 @@ void vlv_wm_sanitize(struct drm_i915_private *dev_priv)
 	mutex_unlock(&dev_priv->wm.wm_mutex);
 }
 
+/*
+ * FIXME should probably kill this and improve
+ * the real watermark readout/sanitation instead
+ */
+static void ilk_init_lp_watermarks(struct drm_i915_private *dev_priv)
+{
+	I915_WRITE(WM3_LP_ILK, I915_READ(WM3_LP_ILK) & ~WM1_LP_SR_EN);
+	I915_WRITE(WM2_LP_ILK, I915_READ(WM2_LP_ILK) & ~WM1_LP_SR_EN);
+	I915_WRITE(WM1_LP_ILK, I915_READ(WM1_LP_ILK) & ~WM1_LP_SR_EN);
+
+	/*
+	 * Don't touch WM1S_LP_EN here.
+	 * Doing so could cause underruns.
+	 */
+}
+
 void ilk_wm_get_hw_state(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct ilk_wm_values *hw = &dev_priv->wm.hw;
 	struct drm_crtc *crtc;
 
+	ilk_init_lp_watermarks(dev_priv);
+
 	for_each_crtc(dev, crtc)
 		ilk_pipe_wm_get_hw_state(crtc);
 
@@ -8213,18 +8231,6 @@ static void g4x_disable_trickle_feed(struct drm_i915_private *dev_priv)
 	}
 }
 
-static void ilk_init_lp_watermarks(struct drm_i915_private *dev_priv)
-{
-	I915_WRITE(WM3_LP_ILK, I915_READ(WM3_LP_ILK) & ~WM1_LP_SR_EN);
-	I915_WRITE(WM2_LP_ILK, I915_READ(WM2_LP_ILK) & ~WM1_LP_SR_EN);
-	I915_WRITE(WM1_LP_ILK, I915_READ(WM1_LP_ILK) & ~WM1_LP_SR_EN);
-
-	/*
-	 * Don't touch WM1S_LP_EN here.
-	 * Doing so could cause underruns.
-	 */
-}
-
 static void ilk_init_clock_gating(struct drm_i915_private *dev_priv)
 {
 	uint32_t dspclk_gate = ILK_VRHUNIT_CLOCK_GATE_DISABLE;
@@ -8258,8 +8264,6 @@ static void ilk_init_clock_gating(struct drm_i915_private *dev_priv)
 		   (I915_READ(DISP_ARB_CTL) |
 		    DISP_FBC_WM_DIS));
 
-	ilk_init_lp_watermarks(dev_priv);
-
 	/*
 	 * Based on the document from hardware guys the following bits
 	 * should be set unconditionally in order to enable FBC.
@@ -8372,8 +8376,6 @@ static void gen6_init_clock_gating(struct drm_i915_private *dev_priv)
 	I915_WRITE(GEN6_GT_MODE,
 		   _MASKED_FIELD(GEN6_WIZ_HASHING_MASK, GEN6_WIZ_HASHING_16x4));
 
-	ilk_init_lp_watermarks(dev_priv);
-
 	I915_WRITE(CACHE_MODE_0,
 		   _MASKED_BIT_DISABLE(CM0_STC_EVICT_DISABLE_LRA_SNB));
 
@@ -8600,8 +8602,6 @@ static void bdw_init_clock_gating(struct drm_i915_private *dev_priv)
 						 I915_GTT_PAGE_SIZE_2M);
 	enum pipe pipe;
 
-	ilk_init_lp_watermarks(dev_priv);
-
 	/* WaSwitchSolVfFArbitrationPriority:bdw */
 	I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) | HSW_ECOCHK_ARB_PRIO_SOL);
 
@@ -8652,8 +8652,6 @@ static void bdw_init_clock_gating(struct drm_i915_private *dev_priv)
 
 static void hsw_init_clock_gating(struct drm_i915_private *dev_priv)
 {
-	ilk_init_lp_watermarks(dev_priv);
-
 	/* L3 caching of data atomics doesn't work -- disable it. */
 	I915_WRITE(HSW_SCRATCH1, HSW_SCRATCH1_L3_DATA_ATOMICS_DISABLE);
 	I915_WRITE(HSW_ROW_CHICKEN3,
@@ -8708,8 +8706,6 @@ static void ivb_init_clock_gating(struct drm_i915_private *dev_priv)
 {
 	uint32_t snpcr;
 
-	ilk_init_lp_watermarks(dev_priv);
-
 	I915_WRITE(ILK_DSPCLK_GATE_D, ILK_VRHUNIT_CLOCK_GATE_DISABLE);
 
 	/* WaDisableEarlyCull:ivb */
-- 
2.15.0