linux-kernel - [PATCH 4.14 22/61] drm/i915: Enable provoking vertex fix on Gen9 systems.

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Date:   Fri,  6 Jul 2018 07:46:46 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kenneth Graunke <kenneth@...tecape.org>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Jani Nikula <jani.nikula@...el.com>
Subject: [PATCH 4.14 22/61] drm/i915: Enable provoking vertex fix on Gen9 systems.

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kenneth Graunke <kenneth@...tecape.org>

commit 7a3727f385dc64773db1c144f6b15c1e9d4735bb upstream.

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@...tecape.org>
Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180615190605.16238-1-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
Cc: stable@...r.kernel.org
(cherry picked from commit b77422f80337d363eed60c8c48db9cb6e33085c9)
Signed-off-by: Jani Nikula <jani.nikula@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/i915/i915_reg.h  |    5 +++++
 drivers/gpu/drm/i915/intel_lrc.c |   12 +++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2484,12 +2484,17 @@ 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_SF_DISABLE_FASTCLIP_CULL		(1 << 5)
 #define  _3D_CHICKEN_SDE_LIMIT_FIFO_POLY_DEPTH(x)	((x)<<1) /* gen8+ */
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1067,11 +1067,21 @@ static u32 *gen9_init_indirectctx_bb(str
 	/* 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 */