[Intel-gfx] [PATCH 8/9] drm/i915/icl: Set graphics mode register for gen11

[Paulo Zanoni]

From: Kelvin Gardiner <kelvin.gardiner at intel.com>

This patch clears a single bit. The bit is 0 by default but expected
not to be set. Explicitly clearing the bit in this patch is intended
to indicate some thinking has occurred, and that we want this bit
cleared and we are not just excepting the default value.

We also stop setting GFX_RUN_LIST_ENABLE, which is correct since that
bit is gone.

v2 (from Paulo): fix indentation.
v3: Changed GEN check to >= 11. Corrected author name.
v4 (from Paulo): improve commit message (Daniele).

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Signed-off-by: Kelvin Gardiner <kelvin.gardiner at intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h  |  2 ++
 drivers/gpu/drm/i915/intel_lrc.c | 18 ++++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 05c57166eee3..3b457990b73c 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2590,6 +2590,8 @@ enum i915_power_well_id {
 #define   GFX_FORWARD_VBLANK_ALWAYS	(1<<5)
 #define   GFX_FORWARD_VBLANK_COND	(2<<5)
 
+#define   GEN11_GFX_DISABLE_LEGACY_MODE	(1<<3)
+
 #define VLV_DISPLAY_BASE 0x180000
 #define VLV_MIPI_BASE VLV_DISPLAY_BASE
 #define BXT_MIPI_BASE 0x60000
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 2fa328d512fc..b298be8e5f20 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1443,8 +1443,22 @@ static void enable_execlists(struct intel_engine_cs *engine)
 	struct drm_i915_private *dev_priv = engine->i915;
 
 	I915_WRITE(RING_HWSTAM(engine->mmio_base), 0xffffffff);
-	I915_WRITE(RING_MODE_GEN7(engine),
-		   _MASKED_BIT_ENABLE(GFX_RUN_LIST_ENABLE));
+
+	/*
+	 * Make sure we're not enabling the new 12-deep CSB
+	 * FIFO as that requires a slightly updated handling
+	 * in the ctx switch irq. Since we're currently only
+	 * using only 2 elements of the enhanced execlists the
+	 * deeper FIFO it's not needed and it's not worth adding
+	 * more statements to the irq handler to support it.
+	 */
+	if (INTEL_GEN(dev_priv) >= 11)
+		I915_WRITE(RING_MODE_GEN7(engine),
+			   _MASKED_BIT_DISABLE(GEN11_GFX_DISABLE_LEGACY_MODE));
+	else
+		I915_WRITE(RING_MODE_GEN7(engine),
+			   _MASKED_BIT_ENABLE(GFX_RUN_LIST_ENABLE));
+
 	I915_WRITE(RING_HWS_PGA(engine->mmio_base),
 		   engine->status_page.ggtt_offset);
 	POSTING_READ(RING_HWS_PGA(engine->mmio_base));
-- 
2.14.3