[Intel-gfx] [PATCH v3] drm/i915/icl: Set graphics mode register for gen11

[Kelvin Gardiner]

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.

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

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 73c9c36..057f90e 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2604,6 +2604,8 @@ 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 dab988f..d4cc5c9 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1500,8 +1500,22 @@ 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));
-- 
1.9.1