drm/i915: implement Haswell DP link train sequence

Previous patch "drm/i915: add basic Haswell DP link train bits"
implemented the basic structure to set the voltage levels and training
patterns. This patch adds the higher-level bits that are part of the
mode set sequence and hot plug.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

3 files changed, 81 insertions, 8 deletions

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 601ffc277a35..81cca482c9dc 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1108,14 +1108,23 @@ void intel_ddi_disable_pipe_clock(struct intel_crtc *intel_crtc)
 
 void intel_ddi_pre_enable(struct intel_encoder *intel_encoder)
 {
-        struct drm_crtc *crtc = intel_encoder->base.crtc;
-        struct drm_i915_private *dev_priv = crtc->dev->dev_private;
+        struct drm_encoder *encoder = &intel_encoder->base;
+        struct drm_crtc *crtc = encoder->crtc;
+        struct drm_i915_private *dev_priv = encoder->dev->dev_private;
         struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
         enum port port = intel_ddi_get_encoder_port(intel_encoder);
 
         WARN_ON(intel_crtc->ddi_pll_sel == PORT_CLK_SEL_NONE);
 
         I915_WRITE(PORT_CLK_SEL(port), intel_crtc->ddi_pll_sel);
+
+        if (intel_encoder->type == INTEL_OUTPUT_DISPLAYPORT) {
+                struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+
+                intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
+                intel_dp_start_link_train(intel_dp);
+                intel_dp_complete_link_train(intel_dp);
+        }
 }
 
 static void intel_wait_ddi_buf_idle(struct drm_i915_private *dev_priv,
@@ -1210,3 +1219,43 @@ void intel_ddi_pll_init(struct drm_device *dev)
         if (val & LCPLL_PLL_DISABLE)
                 DRM_ERROR("LCPLL is disabled\n");
 }
+
+void intel_ddi_prepare_link_retrain(struct drm_encoder *encoder)
+{
+        struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+        struct drm_i915_private *dev_priv = encoder->dev->dev_private;
+        enum port port = intel_dp->port;
+        bool wait;
+        uint32_t val;
+
+        if (I915_READ(DP_TP_CTL(port)) & DP_TP_CTL_ENABLE) {
+                val = I915_READ(DDI_BUF_CTL(port));
+                if (val & DDI_BUF_CTL_ENABLE) {
+                        val &= ~DDI_BUF_CTL_ENABLE;
+                        I915_WRITE(DDI_BUF_CTL(port), val);
+                        wait = true;
+                }
+
+                val = I915_READ(DP_TP_CTL(port));
+                val &= ~(DP_TP_CTL_ENABLE | DP_TP_CTL_LINK_TRAIN_MASK);
+                val |= DP_TP_CTL_LINK_TRAIN_PAT1;
+                I915_WRITE(DP_TP_CTL(port), val);
+                POSTING_READ(DP_TP_CTL(port));
+
+                if (wait)
+                        intel_wait_ddi_buf_idle(dev_priv, port);
+        }
+
+        val = DP_TP_CTL_ENABLE | DP_TP_CTL_MODE_SST |
+              DP_TP_CTL_LINK_TRAIN_PAT1 | DP_TP_CTL_SCRAMBLE_DISABLE;
+        if (intel_dp->link_configuration[1] & DP_LANE_COUNT_ENHANCED_FRAME_EN)
+                val |= DP_TP_CTL_ENHANCED_FRAME_ENABLE;
+        I915_WRITE(DP_TP_CTL(port), val);
+        POSTING_READ(DP_TP_CTL(port));
+
+        intel_dp->DP |= DDI_BUF_CTL_ENABLE;
+        I915_WRITE(DDI_BUF_CTL(port), intel_dp->DP);
+        POSTING_READ(DDI_BUF_CTL(port));
+
+        udelay(600);
+}
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index db6ef136a1b6..f6d86492ba3e 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -102,8 +102,6 @@ bool intel_encoder_is_pch_edp(struct drm_encoder *encoder)
         return is_pch_edp(intel_dp);
 }
 
-static void intel_dp_start_link_train(struct intel_dp *intel_dp);
-static void intel_dp_complete_link_train(struct intel_dp *intel_dp);
 static void intel_dp_link_down(struct intel_dp *intel_dp);
 
 void
@@ -1266,7 +1264,7 @@ static void ironlake_edp_pll_off(struct intel_dp *intel_dp)
 }
 
 /* If the sink supports it, try to set the power state appropriately */
-static void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode)
+void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode)
 {
         int ret, i;
 
@@ -1854,16 +1852,20 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
 }
 
 /* Enable corresponding port and start training pattern 1 */
-static void
+void
 intel_dp_start_link_train(struct intel_dp *intel_dp)
 {
-        struct drm_device *dev = intel_dp->base.base.dev;
+        struct drm_encoder *encoder = &intel_dp->base.base;
+        struct drm_device *dev = encoder->dev;
         int i;
         uint8_t voltage;
         bool clock_recovery = false;
         int voltage_tries, loop_tries;
         uint32_t DP = intel_dp->DP;
 
+        if (IS_HASWELL(dev))
+                intel_ddi_prepare_link_retrain(encoder);
+
         /* Write the link configuration data */
         intel_dp_aux_native_write(intel_dp, DP_LINK_BW_SET,
                                   intel_dp->link_configuration,
@@ -1949,7 +1951,7 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
         intel_dp->DP = DP;
 }
 
-static void
+void
 intel_dp_complete_link_train(struct intel_dp *intel_dp)
 {
         struct drm_device *dev = intel_dp->base.base.dev;
@@ -2035,6 +2037,24 @@ intel_dp_link_down(struct intel_dp *intel_dp)
         struct drm_i915_private *dev_priv = dev->dev_private;
         uint32_t DP = intel_dp->DP;
 
+        /*
+         * DDI code has a strict mode set sequence and we should try to respect
+         * it, otherwise we might hang the machine in many different ways. So we
+         * really should be disabling the port only on a complete crtc_disable
+         * sequence. This function is just called under two conditions on DDI
+         * code:
+         * - Link train failed while doing crtc_enable, and on this case we
+         *   really should respect the mode set sequence and wait for a
+         *   crtc_disable.
+         * - Someone turned the monitor off and intel_dp_check_link_status
+         *   called us. We don't need to disable the whole port on this case, so
+         *   when someone turns the monitor on again,
+         *   intel_ddi_prepare_link_retrain will take care of redoing the link
+         *   train.
+         */
+        if (IS_HASWELL(dev))
+                return;
+
         if (WARN_ON((I915_READ(intel_dp->output_reg) & DP_PORT_EN) == 0))
                 return;
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index d89d428ac6ec..95cbd67ebf97 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -423,6 +423,9 @@ void
 intel_dp_set_m_n(struct drm_crtc *crtc, struct drm_display_mode *mode,
                  struct drm_display_mode *adjusted_mode);
 extern void intel_dp_init_link_config(struct intel_dp *intel_dp);
+extern void intel_dp_start_link_train(struct intel_dp *intel_dp);
+extern void intel_dp_complete_link_train(struct intel_dp *intel_dp);
+extern void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
 extern bool intel_dpd_is_edp(struct drm_device *dev);
 extern void intel_edp_link_config(struct intel_encoder *, int *, int *);
 extern int intel_edp_target_clock(struct intel_encoder *,
@@ -599,5 +602,6 @@ extern void intel_ddi_pre_enable(struct intel_encoder *intel_encoder);
 extern void intel_ddi_post_disable(struct intel_encoder *intel_encoder);
 extern void intel_ddi_put_crtc_pll(struct drm_crtc *crtc);
 extern void intel_ddi_set_pipe_settings(struct drm_crtc *crtc);
+extern void intel_ddi_prepare_link_retrain(struct drm_encoder *encoder);
 
 #endif /* __INTEL_DRV_H__ */