drm/i915: Workaround async flip + VT-d corruption on HSW/BDW
On HSW/BDW with VT-d active the first tile row scanned out
after the first async flip of the frame often ends up corrupted.
Whether the corruption happens or not depends on the scanline
on which the async flip happens, but the behaviour seems very
consistent. Ie. the same set of scanlines (which are most scanlines)
always show the corruption. And another set of scanlines (far less
of them) never shows the corruption.
I discovered that disabling the fetch-stride stretching
feature cures the corruption. This is some kind of TLB related
prefetch thing AFAIK. We already disable it on SNB primary
planes due to a documented workaround. The hardware folks
indicated that disabling this should be fine, so let's go
with that.
And while we're here, let's document the relevant bits on all
pre-skl platforms.
Fixes: 2a636e240c77 ("drm/i915: Implement async flip for ivb/hsw")
Fixes: cda195f13abd ("drm/i915: Implement async flips for bdw")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210220103303.3448-1-ville.syrjala@linux.intel.com
Reviewed-by: Karthik B S <karthik.b.s@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 854ffec..00f1ab5 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -7287,11 +7287,16 @@ static void bdw_init_clock_gating(struct drm_i915_private *dev_priv)
intel_uncore_write(&dev_priv->uncore, CHICKEN_PAR1_1,
intel_uncore_read(&dev_priv->uncore, CHICKEN_PAR1_1) | DPA_MASK_VBLANK_SRD);
- /* WaPsrDPRSUnmaskVBlankInSRD:bdw */
for_each_pipe(dev_priv, pipe) {
+ /* WaPsrDPRSUnmaskVBlankInSRD:bdw */
intel_uncore_write(&dev_priv->uncore, CHICKEN_PIPESL_1(pipe),
intel_uncore_read(&dev_priv->uncore, CHICKEN_PIPESL_1(pipe)) |
BDW_DPRS_MASK_VBLANK_SRD);
+
+ /* Undocumented but fixes async flip + VT-d corruption */
+ if (intel_vtd_active())
+ intel_uncore_rmw(&dev_priv->uncore, CHICKEN_PIPESL_1(pipe),
+ HSW_PRI_STRETCH_MAX_MASK, HSW_PRI_STRETCH_MAX_X1);
}
/* WaVSRefCountFullforceMissDisable:bdw */
@@ -7327,11 +7332,20 @@ static void bdw_init_clock_gating(struct drm_i915_private *dev_priv)
static void hsw_init_clock_gating(struct drm_i915_private *dev_priv)
{
+ enum pipe pipe;
+
/* WaFbcAsynchFlipDisableFbcQueue:hsw,bdw */
intel_uncore_write(&dev_priv->uncore, CHICKEN_PIPESL_1(PIPE_A),
intel_uncore_read(&dev_priv->uncore, CHICKEN_PIPESL_1(PIPE_A)) |
HSW_FBCQ_DIS);
+ for_each_pipe(dev_priv, pipe) {
+ /* Undocumented but fixes async flip + VT-d corruption */
+ if (intel_vtd_active())
+ intel_uncore_rmw(&dev_priv->uncore, CHICKEN_PIPESL_1(pipe),
+ HSW_PRI_STRETCH_MAX_MASK, HSW_PRI_STRETCH_MAX_X1);
+ }
+
/* This is required by WaCatErrorRejectionIssue:hsw */
intel_uncore_write(&dev_priv->uncore, GEN7_SQ_CHICKEN_MBCUNIT_CONFIG,
intel_uncore_read(&dev_priv->uncore, GEN7_SQ_CHICKEN_MBCUNIT_CONFIG) |