[PATCH 21/21] drm/i915: enable RC6 workaround on Haswell

Eugeni Dodonov
2012-06-28T20:08:28Z

For Haswell, on some of the early hardware revisions, it is possible to
run into issues when RC6 state is enabled and when pipes change state.

v2: add comment saying that this is for early revisions only.

Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
---
drivers/gpu/drm/i915/i915_reg.h | 5 +++++
drivers/gpu/drm/i915/intel_pm.c | 12 ++++++++++++
2 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 78b6ba4..fd55e91 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -4512,4 +4512,9 @@
#define SFUSE_STRAP_DDIC_DETECTED (1<<1)
#define SFUSE_STRAP_DDID_DETECTED (1<<0)

+#define WM_DBG 0x45280
+#define WM_DBG_DISALLOW_MULTIPLE_LP (1<<0)
+#define WM_DBG_DISALLOW_MAXFIFO (1<<1)
+#define WM_DBG_DISALLOW_SPRITE (1<<2)
+
#endif /* _I915_REG_H_ */
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 0422e2d..40f2f53 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3601,6 +3601,18 @@ static void haswell_init_clock_gating(struct drm_device *dev)
/* WaDisable4x2SubspanOptimization */
I915_WRITE(CACHE_MODE_1,
_MASKED_BIT_ENABLE(PIXEL_SUBSPAN_COLLECT_OPT_DISABLE));
+
+ /* Work-around rc6 issue */
+ /* XXX: This is a workaround for early silicon revisions and should be
+ * removed later
+ */
+ I915_WRITE(WM_DBG,
+ I915_READ(WM_DBG) |
+ WM_DBG_DISALLOW_MULTIPLE_LP |
+ WM_DBG_DISALLOW_SPRITE |
+ WM_DBG_DISALLOW_MAXFIFO
+ );
+
}

static void ivybridge_init_clock_gating(struct drm_device *dev)
--
1.7.11.1