From c5c98a58990c1b2cf4d94b6759bed239976e5305 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Wed, 5 Feb 2014 12:43:47 +0200
Subject: [PATCH] drm/i915: Add a comment about WIZ hashing vs. thread counts
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Add a comment next to our WIZ hashing setup to remind people about the
link between WIZ hashing disable bit and PS/WM thread counts.

Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/intel_pm.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 151afe53cc7c..3e754fec58b5 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4664,6 +4664,10 @@ static void gen6_init_clock_gating(struct drm_device *dev)
 	/*
 	 * BSpec recoomends 8x4 when MSAA is used,
 	 * however in practice 16x4 seems fastest.
+	 *
+	 * Note that PS/WM thread counts depend on the WIZ hashing
+	 * disable bit, which we don't touch here, but it's good
+	 * to keep in mind (see 3DSTATE_PS and 3DSTATE_WM).
 	 */
 	I915_WRITE(GEN6_GT_MODE,
 		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
@@ -4847,6 +4851,10 @@ static void gen8_init_clock_gating(struct drm_device *dev)
 	/*
 	 * BSpec recommends 8x4 when MSAA is used,
 	 * however in practice 16x4 seems fastest.
+	 *
+	 * Note that PS/WM thread counts depend on the WIZ hashing
+	 * disable bit, which we don't touch here, but it's good
+	 * to keep in mind (see 3DSTATE_PS and 3DSTATE_WM).
 	 */
 	I915_WRITE(GEN7_GT_MODE,
 		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
@@ -4883,6 +4891,10 @@ static void haswell_init_clock_gating(struct drm_device *dev)
 	/*
 	 * BSpec recommends 8x4 when MSAA is used,
 	 * however in practice 16x4 seems fastest.
+	 *
+	 * Note that PS/WM thread counts depend on the WIZ hashing
+	 * disable bit, which we don't touch here, but it's good
+	 * to keep in mind (see 3DSTATE_PS and 3DSTATE_WM).
 	 */
 	I915_WRITE(GEN7_GT_MODE,
 		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
@@ -4971,6 +4983,10 @@ static void ivybridge_init_clock_gating(struct drm_device *dev)
 	/*
 	 * BSpec recommends 8x4 when MSAA is used,
 	 * however in practice 16x4 seems fastest.
+	 *
+	 * Note that PS/WM thread counts depend on the WIZ hashing
+	 * disable bit, which we don't touch here, but it's good
+	 * to keep in mind (see 3DSTATE_PS and 3DSTATE_WM).
 	 */
 	I915_WRITE(GEN7_GT_MODE,
 		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
-- 
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