[PATCH 05/10] drm/i915/dsb: Check DSB engine status.

[Animesh Manna]

As per bspec check for DSB status before programming any
of its register. Inline function added to check the dsb status.

Signed-off-by: Animesh Manna <animesh.manna at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dsb.c | 9 +++++++++
 drivers/gpu/drm/i915/i915_reg.h          | 7 +++++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
index 11dc6d54f254..73ab0b5a1c93 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -17,6 +17,15 @@
 #define DSB_BYTE_EN_SHIFT		20
 #define DSB_REG_VALUE_MASK		0xfffff
 
+static inline bool is_dsb_busy(struct intel_dsb *dsb)
+{
+	struct intel_crtc *crtc = dsb->crtc;
+	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+	enum pipe pipe = crtc->pipe;
+
+	return DSB_STATUS & I915_READ(DSB_CTRL(pipe, dsb->id));
+}
+
 struct intel_dsb *
 intel_dsb_get(struct intel_crtc *crtc)
 {
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 006cffd56be2..a3099f712ae6 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -11676,4 +11676,11 @@ enum skl_power_gate {
 #define PORT_TX_DFLEXDPCSSS(fia)		_MMIO_FIA((fia), 0x00894)
 #define   DP_PHY_MODE_STATUS_NOT_SAFE(tc_port)		(1 << (tc_port))
 
+/* This register controls the Display State Buffer (DSB) engines. */
+#define _DSBSL_INSTANCE_BASE		0x70B00
+#define DSBSL_INSTANCE(pipe, id)	(_DSBSL_INSTANCE_BASE + \
+					 (pipe) * 0x1000 + (id) * 100)
+#define DSB_CTRL(pipe, id)		_MMIO(DSBSL_INSTANCE(pipe, id) + 0x8)
+#define   DSB_STATUS			(1 << 0)
+
 #endif /* _I915_REG_H_ */
-- 
2.22.0