[Intel-gfx] [PATCH 35/50] drm/i915/bdw: Add forcewake lock around ELSP writes

[oscar.mateo at intel.com]

From: Thomas Daniel <thomas.daniel at intel.com>

BSPEC says: SW must set Force Wakeup bit to prevent GT from
entering C6 while ELSP writes are in progress.

Signed-off-by: Thomas Daniel <thomas.daniel at intel.com>
Acked-by: Oscar Mateo <oscar.mateo at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h  |  1 +
 drivers/gpu/drm/i915/intel_lrc.c | 15 +++++++++++----
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 208a4bd..6b39fed 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2694,6 +2694,7 @@ int vlv_freq_opcode(struct drm_i915_private *dev_priv, int val);
 
 #define I915_READ(reg)		dev_priv->uncore.funcs.mmio_readl(dev_priv, (reg), true)
 #define I915_WRITE(reg, val)	dev_priv->uncore.funcs.mmio_writel(dev_priv, (reg), (val), true)
+#define I915_RAW_WRITE(reg, val)	writel(val, dev_priv->regs + reg)
 #define I915_READ_NOTRACE(reg)		dev_priv->uncore.funcs.mmio_readl(dev_priv, (reg), false)
 #define I915_WRITE_NOTRACE(reg, val)	dev_priv->uncore.funcs.mmio_writel(dev_priv, (reg), (val), false)
 
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 2eb1c28..54cbb4b 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -141,14 +141,21 @@ static void submit_execlist(struct intel_engine *ring,
 	desc[3] = (u32)(temp >> 32);
 	desc[2] = (u32)temp;
 
-	I915_WRITE(RING_ELSP(ring), desc[1]);
-	I915_WRITE(RING_ELSP(ring), desc[0]);
-	I915_WRITE(RING_ELSP(ring), desc[3]);
+	/* Set Force Wakeup bit to prevent GT from entering C6 while
+	 * ELSP writes are in progress */
+	gen6_gt_force_wake_get(dev_priv, FORCEWAKE_ALL);
+
+	I915_RAW_WRITE(RING_ELSP(ring), desc[1]);
+	I915_RAW_WRITE(RING_ELSP(ring), desc[0]);
+	I915_RAW_WRITE(RING_ELSP(ring), desc[3]);
 	/* The context is automatically loaded after the following */
-	I915_WRITE(RING_ELSP(ring), desc[2]);
+	I915_RAW_WRITE(RING_ELSP(ring), desc[2]);
 
 	/* ELSP is a write only register, so this serves as a posting read */
 	POSTING_READ(RING_EXECLIST_STATUS(ring));
+
+	/* Release Force Wakeup */
+	gen6_gt_force_wake_put(dev_priv, FORCEWAKE_ALL);
 }
 
 static int gen8_switch_context(struct intel_engine *ring,
-- 
1.9.0