[Intel-gfx] [PATCH v8 06/10] drm/i915/dsb: functions to enable/disable DSB engine.

[Animesh Manna]

DSB will be used for performance improvement for some special scenario.
DSB engine will be enabled based on need and after completion of its work
will be disabled. Api added for enable/disable operation by using DSB_CTRL
register.

v1: Initial version.
v2: POSTING_READ added after writing control register. (Shashank)
v3: cosmetic changes done. (Shashank)

Cc: Michel Thierry <michel.thierry at intel.com>
Cc: Jani Nikula <jani.nikula at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Shashank Sharma <shashank.sharma at intel.com>
Reviewed-by: Shashank Sharma <shashank.sharma at intel.com>
Signed-off-by: Animesh Manna <animesh.manna at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dsb.c | 40 ++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_reg.h          |  1 +
 2 files changed, 41 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
index bcc4d16c3b4b..e00ec196133e 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -26,6 +26,46 @@ static inline bool is_dsb_busy(struct intel_dsb *dsb)
 	return DSB_STATUS & I915_READ(DSB_CTRL(pipe, dsb->id));
 }
 
+static inline bool intel_dsb_enable_engine(struct intel_dsb *dsb)
+{
+	struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
+	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+	enum pipe pipe = crtc->pipe;
+	u32 dsb_ctrl;
+
+	dsb_ctrl = I915_READ(DSB_CTRL(pipe, dsb->id));
+	if (DSB_STATUS & dsb_ctrl) {
+		DRM_DEBUG_KMS("DSB engine is busy.\n");
+		return false;
+	}
+
+	dsb_ctrl |= DSB_ENABLE;
+	I915_WRITE(DSB_CTRL(pipe, dsb->id), dsb_ctrl);
+
+	POSTING_READ(DSB_CTRL(pipe, dsb->id));
+	return true;
+}
+
+static inline bool intel_dsb_disable_engine(struct intel_dsb *dsb)
+{
+	struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
+	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+	enum pipe pipe = crtc->pipe;
+	u32 dsb_ctrl;
+
+	dsb_ctrl = I915_READ(DSB_CTRL(pipe, dsb->id));
+	if (DSB_STATUS & dsb_ctrl) {
+		DRM_DEBUG_KMS("DSB engine is busy.\n");
+		return false;
+	}
+
+	dsb_ctrl &= ~DSB_ENABLE;
+	I915_WRITE(DSB_CTRL(pipe, dsb->id), dsb_ctrl);
+
+	POSTING_READ(DSB_CTRL(pipe, dsb->id));
+	return true;
+}
+
 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 01ed543c28e6..5ca90f66393c 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -11692,6 +11692,7 @@ enum skl_power_gate {
 #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_ENABLE			(1 << 31)
 #define   DSB_STATUS			(1 << 0)
 
 #endif /* _I915_REG_H_ */
-- 
2.22.0