Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled
"Display flickering may occur when both FBC (Frame Buffer Compression)
and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
and in use by the display controller."
Ville found the w/a name in the database:
WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
v2: Log when the quirk is applied.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 2 ++
drivers/gpu/drm/i915/intel_fbc.c | 15 +++++++++++++++
2 files changed, 17 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index afe1ff67557c..02b888684de8 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2577,6 +2577,8 @@ struct drm_i915_cmd_table {
#define INTEL_GEN(p) (INTEL_INFO(p)->gen)
#define INTEL_DEVID(p) (INTEL_INFO(p)->device_id)
+#define mkwrite_intel_info(p) ((struct intel_device_info *)INTEL_INFO(p))
+
#define REVID_FOREVER 0xff
#define INTEL_REVID(p) (__I915__(p)->drm.pdev->revision)
diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index fddba1eed5ad..b3c67021771b 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -1230,6 +1230,18 @@ void intel_fbc_init_pipe_state(struct drm_i915_private *dev_priv)
dev_priv->fbc.visible_pipes_mask |= (1 << crtc->pipe);
}
+static bool need_fbc_wa(struct drm_i915_private *dev_priv)
+{
+#ifdef CONFIG_INTEL_IOMMU
+ /* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
+ if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {
+ DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
+ return true;
+ }
+#endif
+ return false;
+}
+
/**
* intel_fbc_init - Initialize FBC
* @dev_priv: the i915 device
@@ -1247,6 +1259,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
fbc->active = false;
fbc->work.scheduled = false;
+ if (need_fbc_wa(dev_priv))
+ mkwrite_intel_info(dev_priv)->has_fbc = false;
+
if (!HAS_FBC(dev_priv)) {
fbc->no_fbc_reason = "unsupported by this chipset";
return;
--
2.8.1
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