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. v3: Ensure i915.enable_fbc is false when !HAS_FBC() Signed-off-by: Chris Wilson <[email protected]> Cc: Paulo Zanoni <[email protected]> Cc: Ville Syrjälä <[email protected]> --- Paulo, I was under the impression you wanted to ack this as a known issue? -Chris --- drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c index 06d3a86828fc..17343baf25ea 100644 --- a/drivers/gpu/drm/i915/intel_fbc.c +++ b/drivers/gpu/drm/i915/intel_fbc.c @@ -1240,12 +1240,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv) if (i915.enable_fbc >= 0) return !!i915.enable_fbc; + if (!HAS_FBC(dev_priv)) + return 0; + if (IS_BROADWELL(dev_priv)) return 1; return 0; } +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 @@ -1263,6 +1279,9 @@ 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; + i915.enable_fbc = intel_sanitize_fbc_option(dev_priv); DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc); -- 2.8.1 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
