drm/i915: Enable provoking vertex fix on Gen9 systems.

The SF and clipper units mishandle the provoking vertex in some cases,
which can cause misrendering with shaders that use flat shaded inputs.

There are chicken bits in 3D_CHICKEN3 (for SF) and FF_SLICE_CHICKEN
(for the clipper) that work around the issue.  These registers are
unfortunately not part of the logical context (even the power context),
and so we must reload them every time we start executing in a context.

Bugzilla: https://bugs.freedesktop.org/103047
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180615190605.16238-1-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: stable@vger.kernel.org
(cherry picked from commit b77422f80337d363eed60c8c48db9cb6e33085c9)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index f11bb213ec0784e4c50db5bd0ea0647a5419e0e1..7720569f20244114e027dca6b810b182771cfcee 100644 (file)
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2425,12 +2425,17 @@ enum i915_power_well_id {
 #define _3D_CHICKEN    _MMIO(0x2084)
 #define  _3D_CHICKEN_HIZ_PLANE_DISABLE_MSAA_4X_SNB     (1 << 10)
 #define _3D_CHICKEN2   _MMIO(0x208c)
+
+#define FF_SLICE_CHICKEN       _MMIO(0x2088)
+#define  FF_SLICE_CHICKEN_CL_PROVOKING_VERTEX_FIX      (1 << 1)
+
 /* Disables pipelining of read flushes past the SF-WIZ interface.
  * Required on all Ironlake steppings according to the B-Spec, but the
  * particular danger of not doing so is not specified.
  */
 # define _3D_CHICKEN2_WM_READ_PIPELINED                        (1 << 14)
 #define _3D_CHICKEN3   _MMIO(0x2090)
+#define  _3D_CHICKEN_SF_PROVOKING_VERTEX_FIX           (1 << 12)
 #define  _3D_CHICKEN_SF_DISABLE_OBJEND_CULL            (1 << 10)
 #define  _3D_CHICKEN3_AA_LINE_QUALITY_FIX_ENABLE       (1 << 5)
 #define  _3D_CHICKEN3_SF_DISABLE_FASTCLIP_CULL         (1 << 5)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index f3968580e5e22f6f724f500dba2c502e4118a378..7c4c8fb1dae465bdaba562ed536e68918b7eb6b8 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1545,11 +1545,21 @@ static u32 *gen9_init_indirectctx_bb(struct intel_engine_cs *engine, u32 *batch)
        /* WaFlushCoherentL3CacheLinesAtContextSwitch:skl,bxt,glk */
        batch = gen8_emit_flush_coherentl3_wa(engine, batch);
 
+       *batch++ = MI_LOAD_REGISTER_IMM(3);
+
        /* WaDisableGatherAtSetShaderCommonSlice:skl,bxt,kbl,glk */
-       *batch++ = MI_LOAD_REGISTER_IMM(1);
        *batch++ = i915_mmio_reg_offset(COMMON_SLICE_CHICKEN2);
        *batch++ = _MASKED_BIT_DISABLE(
                        GEN9_DISABLE_GATHER_AT_SET_SHADER_COMMON_SLICE);
+
+       /* BSpec: 11391 */
+       *batch++ = i915_mmio_reg_offset(FF_SLICE_CHICKEN);
+       *batch++ = _MASKED_BIT_ENABLE(FF_SLICE_CHICKEN_CL_PROVOKING_VERTEX_FIX);
+
+       /* BSpec: 11299 */
+       *batch++ = i915_mmio_reg_offset(_3D_CHICKEN3);
+       *batch++ = _MASKED_BIT_ENABLE(_3D_CHICKEN_SF_PROVOKING_VERTEX_FIX);
+
        *batch++ = MI_NOOP;
 
        /* WaClearSlmSpaceAtContextSwitch:kbl */