[Intel-gfx] [PATCH 5/6] drm/i915/bdw: Add support for DRRS to switch RR

[Vandana Kannan]

For Broadwell, there is one instance of Transcoder MN values per transcoder.
For dynamic switching between multiple refreshr rates, M/N values may be
reprogrammed on the fly. Link N programming triggers update of all data and
link M & N registers and the new M/N values will be used in the next frame
that is output.

v2: Incorporated Chris's review comments
Changed to check for gen >=8 or gen > 5 before setting M/N registers

v3: Incorporated Jani's review comments
Re-use cpu_transcoder_set_m_n for BDW.

Signed-off-by: Vandana Kannan <vandana.kannan at intel.com>
Signed-off-by: Pradeep Bhat <pradeep.bhat at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |    2 +-
 drivers/gpu/drm/i915/intel_dp.c      |   25 +++++++++++++++++++------
 drivers/gpu/drm/i915/intel_drv.h     |    2 ++
 3 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index c309561..f492b51 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5120,7 +5120,7 @@ static void intel_pch_transcoder_set_m_n(struct intel_crtc *crtc,
 	I915_WRITE(PCH_TRANS_LINK_N1(pipe), m_n->link_n);
 }
 
-static void intel_cpu_transcoder_set_m_n(struct intel_crtc *crtc,
+void intel_cpu_transcoder_set_m_n(struct intel_crtc *crtc,
 					 struct intel_link_m_n *m_n)
 {
 	struct drm_device *dev = crtc->base.dev;
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 4f0281a..6cdbb38 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -743,11 +743,15 @@ intel_dp_set_m2_n2(struct intel_crtc *crtc, struct intel_link_m_n *m_n)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	enum transcoder transcoder = crtc->config.cpu_transcoder;
 
-	I915_WRITE(PIPE_DATA_M2(transcoder),
-		TU_SIZE(m_n->tu) | m_n->gmch_m);
-	I915_WRITE(PIPE_DATA_N2(transcoder), m_n->gmch_n);
-	I915_WRITE(PIPE_LINK_M2(transcoder), m_n->link_m);
-	I915_WRITE(PIPE_LINK_N2(transcoder), m_n->link_n);
+	if (INTEL_INFO(dev)->gen >= 8) {
+		intel_cpu_transcoder_set_m_n(crtc, m_n);
+	} else if (INTEL_INFO(dev)->gen > 6) {
+		I915_WRITE(PIPE_DATA_M2(transcoder),
+			TU_SIZE(m_n->tu) | m_n->gmch_m);
+		I915_WRITE(PIPE_DATA_N2(transcoder), m_n->gmch_n);
+		I915_WRITE(PIPE_LINK_M2(transcoder), m_n->link_m);
+		I915_WRITE(PIPE_LINK_N2(transcoder), m_n->link_n);
+	}
 }
 
 bool
@@ -3704,7 +3708,16 @@ void intel_dp_set_drrs_state(struct drm_device *dev, int refresh_rate)
 		return;
 	}
 
-	if (INTEL_INFO(dev)->gen > 6 && INTEL_INFO(dev)->gen < 8) {
+	if (INTEL_INFO(dev)->gen >= 8) {
+		switch (index) {
+		case DRRS_HIGH_RR:
+			intel_dp_set_m2_n2(intel_crtc, &config->dp_m_n);
+			break;
+		case DRRS_LOW_RR:
+			intel_dp_set_m2_n2(intel_crtc, &config->dp_m2_n2);
+			break;
+		};
+	} else if (INTEL_INFO(dev)->gen > 6) {
 		reg = PIPECONF(intel_crtc->config.cpu_transcoder);
 		val = I915_READ(reg);
 		if (index > DRRS_HIGH_RR) {
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 570cc47..e4b479e 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -770,6 +770,8 @@ int valleyview_get_vco(struct drm_i915_private *dev_priv);
 void intel_mode_from_pipe_config(struct drm_display_mode *mode,
 				 struct intel_crtc_config *pipe_config);
 int intel_format_to_fourcc(int format);
+void intel_cpu_transcoder_set_m_n(struct intel_crtc *crtc,
+				struct intel_link_m_n *m_n);
 
 /* intel_dp.c */
 void intel_dp_init(struct drm_device *dev, int output_reg, enum port port);
-- 
1.7.9.5