patches.baytrail/0876-drm-i915-write-D_COMP-using-the-mailbox.patch

From 1c2a2f772b86a80ed40f690fb971b8b2d52575c2 Mon Sep 17 00:00:00 2001
From: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date: Tue, 10 Sep 2013 19:36:37 -0300
Subject: drm/i915: write D_COMP using the mailbox

You can't write it using the MCHBAR mirror, the write will just get
dropped.

This should make us BSpec-compliant, but there's no real bug I could
reproduce that is fixed by this patch.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
[danvet: Fix spelling mistake in the comment that Damien spotted.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

(cherry picked from commit 515b239269fb67fd167676d335a56ef0c13e53d5)
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h      |    4 ++++
 drivers/gpu/drm/i915/intel_display.c |   10 ++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1443,6 +1443,8 @@
  * device 0 function 0's pci config register 0x44 or 0x48 and matches it in
  * every way.  It is not accessible from the CP register read instructions.
  *
+ * Starting from Haswell, you can't write registers using the MCHBAR mirror,
+ * just read.
  */
 #define MCHBAR_MIRROR_BASE	0x10000
 
@@ -4730,6 +4732,8 @@
 #define   GEN6_PCODE_READ_MIN_FREQ_TABLE	0x9
 #define	  GEN6_PCODE_WRITE_RC6VIDS		0x4
 #define	  GEN6_PCODE_READ_RC6VIDS		0x5
+#define   GEN6_PCODE_READ_D_COMP		0x10
+#define   GEN6_PCODE_WRITE_D_COMP		0x11
 #define   GEN6_ENCODE_RC6_VID(mv)		(((mv) - 245) / 5)
 #define   GEN6_DECODE_RC6_VID(vids)		(((vids) * 5) + 245)
 #define GEN6_PCODE_DATA				0x138128
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6135,7 +6135,10 @@ void hsw_disable_lcpll(struct drm_i915_p
 
 	val = I915_READ(D_COMP);
 	val |= D_COMP_COMP_DISABLE;
-	I915_WRITE(D_COMP, val);
+	mutex_lock(&dev_priv->rps.hw_lock);
+	if (sandybridge_pcode_write(dev_priv, GEN6_PCODE_WRITE_D_COMP, val))
+		DRM_ERROR("Failed to disable D_COMP\n");
+	mutex_unlock(&dev_priv->rps.hw_lock);
 	POSTING_READ(D_COMP);
 	ndelay(100);
 
@@ -6177,7 +6180,10 @@ void hsw_restore_lcpll(struct drm_i915_p
 	val = I915_READ(D_COMP);
 	val |= D_COMP_COMP_FORCE;
 	val &= ~D_COMP_COMP_DISABLE;
-	I915_WRITE(D_COMP, val);
+	mutex_lock(&dev_priv->rps.hw_lock);
+	if (sandybridge_pcode_write(dev_priv, GEN6_PCODE_WRITE_D_COMP, val))
+		DRM_ERROR("Failed to enable D_COMP\n");
+	mutex_unlock(&dev_priv->rps.hw_lock);
 	POSTING_READ(D_COMP);
 
 	val = I915_READ(LCPLL_CTL);