This workaround is for fbc working with rc6 on skylake. Bspec
states that setting this bit needs to be coordinated with uncore
but offers no further details.
v2: rebase
References: HSD#4712857
Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
Reviewed-by: Matthew Auld <matthew.auld@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_reg.h | 3 +++
drivers/gpu/drm/i915/intel_pm.c | 6 ++++++
2 files changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 1a9d76dd5550..e0c2bd93a0ac 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2167,6 +2167,9 @@ enum skl_disp_power_wells {
#define FBC_LL_SIZE (1536)
+#define FBC_LLC_READ_CTRL _MMIO(0x9044)
+#define FBC_LLC_FULLY_OPEN (1<<30)
+
/* Framebuffer compression for GM45+ */
#define DPFC_CB_BASE _MMIO(0x3200)
#define DPFC_CONTROL _MMIO(0x3208)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index afa5eeed5859..d8eb23f0ccbf 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6992,7 +6992,13 @@ static void kabylake_init_clock_gating(struct drm_device *dev)
static void skylake_init_clock_gating(struct drm_device *dev)
{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+
gen9_init_clock_gating(dev);
+
+ /* WAC6entrylatency:skl */
+ I915_WRITE(FBC_LLC_READ_CTRL, I915_READ(FBC_LLC_READ_CTRL) |
+ FBC_LLC_FULLY_OPEN);
}
static void broadwell_init_clock_gating(struct drm_device *dev)
--
2.7.4
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