[Intel-gfx] [PATCH 14/27] drm/i915/kbl: Add WaDisableDynamicCreditSharing

[Mika Kuoppala]

Bspec states that we need to turn off dynamic credit
sharing on kbl revid a0 and b0. This happens by writing bit 28
on 0x4ab8.

References: HSD#2225601, HSD#2226938, HSD#2225763
Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
Reviewed-by: Matthew Auld <matthew.auld at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h         | 3 +++
 drivers/gpu/drm/i915/intel_ringbuffer.c | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index b49c39bd8abb..eb9875883379 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1672,6 +1672,9 @@ enum skl_disp_power_wells {
 
 #define GEN7_TLB_RD_ADDR	_MMIO(0x4700)
 
+#define GAMT_CHKN_BIT_REG	_MMIO(0x4ab8)
+#define   GAMT_CHKN_DISABLE_DYNAMIC_CREDIT_SHARING	(1<<28)
+
 #if 0
 #define PRB0_TAIL	_MMIO(0x2030)
 #define PRB0_HEAD	_MMIO(0x2034)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 50379e863ae3..d1c02ed20f37 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1199,6 +1199,11 @@ static int kbl_init_workarounds(struct intel_engine_cs *engine)
 	I915_WRITE(GEN8_GARBCNTL, (I915_READ(GEN8_GARBCNTL) |
 				   GEN9_GAPS_TSV_CREDIT_DISABLE));
 
+	/* WaDisableDynamicCreditSharing:kbl */
+	if (IS_KBL_REVID(dev_priv, 0, KBL_REVID_B0))
+		WA_SET_BIT(GAMT_CHKN_BIT_REG,
+			   GAMT_CHKN_DISABLE_DYNAMIC_CREDIT_SHARING);
+
 	/* WaDisableFenceDestinationToSLM:kbl (pre-prod) */
 	if (IS_KBL_REVID(dev_priv, KBL_REVID_A0, KBL_REVID_A0))
 		WA_SET_BIT_MASKED(HDC_CHICKEN0,
-- 
2.7.4