drm/i915: Apply B-spec mandated workaround for read flushes on Ironlake.
This is not known to fix any particular bugs we have, but the spec
says to do it, and the BIOS hadn't already set it up on my system.
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 77b3494..5ab4035 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5818,6 +5818,12 @@
ILK_DPFC_DIS2 |
ILK_CLK_FBC);
}
+
+ if (IS_GEN5(dev)) {
+ I915_WRITE(_3D_CHICKEN2,
+ _3D_CHICKEN2_WM_READ_PIPELINED << 16 |
+ _3D_CHICKEN2_WM_READ_PIPELINED);
+ }
return;
} else if (IS_G4X(dev)) {
uint32_t dspclk_gate;