drm/i915: gen7: implement rczunit workaround

commit eae66b50c760233fad526edf4a0d327be17a055d upstream.

This is yet another workaround related to clock gating which we need on
Ivy Bridge.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=41353
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44610
Tested-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index a26d5b0..4e2e261 100644 (file)
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3476,6 +3476,7 @@
 #define    GT_FIFO_NUM_RESERVED_ENTRIES                20
 
 #define GEN6_UCGCTL2                           0x9404
+# define GEN6_RCZUNIT_CLOCK_GATE_DISABLE               (1 << 13)
 # define GEN6_RCPBUNIT_CLOCK_GATE_DISABLE              (1 << 12)
 # define GEN6_RCCUNIT_CLOCK_GATE_DISABLE               (1 << 11)
 

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 573f485..31c1432 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8248,6 +8248,11 @@ static void ivybridge_init_clock_gating(struct drm_device *dev)
        I915_WRITE(WM2_LP_ILK, 0);
        I915_WRITE(WM1_LP_ILK, 0);
 
+       /* According to the spec, bit 13 (RCZUNIT) must be set on IVB.
+        * This implements the WaDisableRCZUnitClockGating workaround.
+        */
+       I915_WRITE(GEN6_UCGCTL2, GEN6_RCZUNIT_CLOCK_GATE_DISABLE);
+
        I915_WRITE(ILK_DSPCLK_GATE, IVB_VRHUNIT_CLK_GATE);
 
        for_each_pipe(pipe) {