drm/i915: Disable tesselation clock gating on tgl A0

Disable TEDOP clock gating flow by programming 0x20A0[19] = 1

References: HSDES#1407928979
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200207155138.30978-1-mika.kuoppala@linux.intel.com
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index dc20672..b62029a 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3165,6 +3165,7 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 #define GEN7_FF_THREAD_MODE		_MMIO(0x20a0)
 #define   GEN7_FF_SCHED_MASK		0x0077070
 #define   GEN8_FF_DS_REF_CNT_FFME	(1 << 19)
+#define   GEN12_FF_TESSELATION_DOP_GATE_DISABLE BIT(19)
 #define   GEN7_FF_TS_SCHED_HS1		(0x5 << 16)
 #define   GEN7_FF_TS_SCHED_HS0		(0x3 << 16)
 #define   GEN7_FF_TS_SCHED_LOAD_BALANCE	(0x1 << 16)