From: Vandana Kannan <vandana.kan...@intel.com>

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: [By Ram]: intel_dp_set_m_n() is rewritten to accommodate
        gen >= 8 [Rodrigo]

Signed-off-by: Vandana Kannan <vandana.kan...@intel.com>
Signed-off-by: Pradeep Bhat <pradeep.b...@intel.com>
Signed-off-by: Ramalingam C <ramalinga...@intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |   36 ++++++++++++++++++++++------------
 drivers/gpu/drm/i915/intel_dp.c      |   16 +++++++++++++--
 drivers/gpu/drm/i915/intel_drv.h     |   11 ++++++++++-
 3 files changed, 47 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c 
b/drivers/gpu/drm/i915/intel_display.c
index 01dc80b..5712686 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -88,9 +88,6 @@ static int intel_framebuffer_init(struct drm_device *dev,
                                  struct drm_i915_gem_object *obj);
 static void i9xx_set_pipeconf(struct intel_crtc *intel_crtc);
 static void intel_set_pipe_timings(struct intel_crtc *intel_crtc);
-static void intel_cpu_transcoder_set_m_n(struct intel_crtc *crtc,
-                                        struct intel_link_m_n *m_n,
-                                        struct intel_link_m_n *m2_n2);
 static void ironlake_set_pipeconf(struct drm_crtc *crtc);
 static void haswell_set_pipeconf(struct drm_crtc *crtc);
 static void intel_set_pipe_csc(struct drm_crtc *crtc);
@@ -4289,7 +4286,7 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
                intel_prepare_shared_dpll(intel_crtc);
 
        if (intel_crtc->config->has_dp_encoder)
-               intel_dp_set_m_n(intel_crtc);
+               intel_dp_set_m_n(intel_crtc, M1_N1);
 
        intel_set_pipe_timings(intel_crtc);
 
@@ -4397,7 +4394,7 @@ static void haswell_crtc_enable(struct drm_crtc *crtc)
                intel_enable_shared_dpll(intel_crtc);
 
        if (intel_crtc->config->has_dp_encoder)
-               intel_dp_set_m_n(intel_crtc);
+               intel_dp_set_m_n(intel_crtc, M1_N1);
 
        intel_set_pipe_timings(intel_crtc);
 
@@ -5011,7 +5008,7 @@ static void valleyview_crtc_enable(struct drm_crtc *crtc)
        }
 
        if (intel_crtc->config->has_dp_encoder)
-               intel_dp_set_m_n(intel_crtc);
+               intel_dp_set_m_n(intel_crtc, M1_N1);
 
        intel_set_pipe_timings(intel_crtc);
 
@@ -5087,7 +5084,7 @@ static void i9xx_crtc_enable(struct drm_crtc *crtc)
        i9xx_set_pll_dividers(intel_crtc);
 
        if (intel_crtc->config->has_dp_encoder)
-               intel_dp_set_m_n(intel_crtc);
+               intel_dp_set_m_n(intel_crtc, M1_N1);
 
        intel_set_pipe_timings(intel_crtc);
 
@@ -5828,9 +5825,9 @@ 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,
-                                        struct intel_link_m_n *m_n,
-                                        struct intel_link_m_n *m2_n2)
+void intel_cpu_transcoder_set_m_n(struct intel_crtc *crtc,
+                                struct intel_link_m_n *m_n,
+                                struct intel_link_m_n *m2_n2)
 {
        struct drm_device *dev = crtc->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
@@ -5862,13 +5859,26 @@ static void intel_cpu_transcoder_set_m_n(struct 
intel_crtc *crtc,
        }
 }
 
-void intel_dp_set_m_n(struct intel_crtc *crtc)
+void intel_dp_set_m_n(struct intel_crtc *crtc, enum link_m_n_set m_n)
 {
+       struct intel_link_m_n *dp_m_n, *dp_m2_n2 = NULL;
+
+       if (m_n == M1_N1) {
+               dp_m_n = &crtc->config->dp_m_n;
+               dp_m2_n2 = &crtc->config->dp_m2_n2;
+       } else if (m_n == M2_N2) {
+               /* Only one register programming is supported. And m_n value
+                * corresponding to downclock mode needs to be programmed */
+               dp_m_n = &crtc->config->dp_m2_n2;
+       } else {
+               DRM_ERROR("Unsupported divider value\n");
+               return;
+       }
+
        if (crtc->config->has_pch_encoder)
                intel_pch_transcoder_set_m_n(crtc, &crtc->config->dp_m_n);
        else
-               intel_cpu_transcoder_set_m_n(crtc, &crtc->config->dp_m_n,
-                                                  &crtc->config->dp_m2_n2);
+               intel_cpu_transcoder_set_m_n(crtc, dp_m_n, dp_m2_n2);
 }
 
 static void vlv_update_pll(struct intel_crtc *crtc,
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 955aca3..592ca3d 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4803,12 +4803,24 @@ static 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_m_n(intel_crtc, M1_N1);
+                       break;
+               case DRRS_LOW_RR:
+                       intel_dp_set_m_n(intel_crtc, M2_N2);
+                       break;
+               case DRRS_MAX_RR:
+               default:
+                       DRM_ERROR("Unsupported refreshrate type\n");
+               }
+       } else if (INTEL_INFO(dev)->gen > 6) {
                reg = PIPECONF(intel_crtc->config->cpu_transcoder);
                val = I915_READ(reg);
+
                if (index > DRRS_HIGH_RR) {
                        val |= PIPECONF_EDP_RR_MODE_SWITCH;
-                       intel_dp_set_m_n(intel_crtc);
                } else {
                        val &= ~PIPECONF_EDP_RR_MODE_SWITCH;
                }
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index a31dc103..193ccda 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -587,6 +587,12 @@ struct intel_hdmi {
 struct intel_dp_mst_encoder;
 #define DP_MAX_DOWNSTREAM_PORTS                0x10
 
+/* enum to indicate the m_n value from calculated list */
+enum link_m_n_set {
+       M1_N1 = 0,
+       M2_N2
+};
+
 struct intel_dp {
        uint32_t output_reg;
        uint32_t aux_ch_ctl_reg;
@@ -979,7 +985,10 @@ void hsw_enable_pc8(struct drm_i915_private *dev_priv);
 void hsw_disable_pc8(struct drm_i915_private *dev_priv);
 void intel_dp_get_m_n(struct intel_crtc *crtc,
                      struct intel_crtc_state *pipe_config);
-void intel_dp_set_m_n(struct intel_crtc *crtc);
+void intel_dp_set_m_n(struct intel_crtc *crtc, enum link_m_n_set m_n);
+void intel_cpu_transcoder_set_m_n(struct intel_crtc *crtc,
+                                struct intel_link_m_n *m_n,
+                                struct intel_link_m_n *m2_n2);
 int intel_dotclock_calculate(int link_freq, const struct intel_link_m_n *m_n);
 void
 ironlake_check_encoder_dotclock(const struct intel_crtc_state *pipe_config,
-- 
1.7.9.5

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