From: Ville Syrjälä <ville.syrj...@linux.intel.com>

When we pick a new power sequencer for the port but we're not doing a
full modeset, the power sequencer may have locked on to another port.
So kick it a bit to make sure it controls the port we want.

Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 57 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 240bc98..c2b3112 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -288,6 +288,51 @@ intel_dp_init_panel_power_sequencer_registers(struct 
drm_device *dev,
                                              struct intel_dp *intel_dp,
                                              struct edp_power_seq *out);
 
+static void
+vlv_power_sequencer_kick(struct intel_dp *intel_dp,
+                        enum pipe pipe)
+{
+       struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+       struct drm_device *dev = intel_dig_port->base.base.dev;
+       struct drm_i915_private *dev_priv = dev->dev_private;
+       uint32_t DP;
+
+       /* Preserve the BIOS-computed detected bit. This is
+        * supposed to be read-only.
+        */
+       DP = I915_READ(intel_dp->output_reg) & DP_DETECTED;
+       DP |= DP_VOLTAGE_0_4 | DP_PRE_EMPHASIS_0;
+       DP |= DP_PORT_WIDTH(intel_dp->lane_count);
+
+       if (!IS_CHERRYVIEW(dev)) {
+               if (pipe == PIPE_B)
+                       DP |= DP_PIPEB_SELECT;
+       } else {
+               DP |= DP_PIPE_SELECT_CHV(pipe);
+       }
+
+       /*
+        * Need to enable the port with idle pattern to allow the power
+        * sequencer to lock into the port. Otherwise the power sequence
+        * (including vdd force bit!) doesn't work on this port.
+        *
+        * FIXME do we need a clock from the DPLL?
+        * FIXME and what if the pipe is active, does it matter?
+        */
+       DP |= DP_PORT_EN | DP_LINK_TRAIN_PAT_IDLE;
+
+       I915_WRITE(intel_dp->output_reg, DP);
+       POSTING_READ(intel_dp->output_reg);
+
+       intel_edp_panel_vdd_on(intel_dp);
+       intel_edp_panel_on(intel_dp);
+       intel_edp_panel_off(intel_dp);
+
+       I915_WRITE(intel_dp->output_reg, DP & ~DP_PORT_EN);
+       POSTING_READ(intel_dp->output_reg);
+       msleep(intel_dp->panel_power_down_delay);
+}
+
 static enum pipe
 vlv_power_sequencer_pipe(struct intel_dp *intel_dp)
 {
@@ -333,6 +378,15 @@ vlv_power_sequencer_pipe(struct intel_dp *intel_dp)
        intel_dp_init_panel_power_sequencer_registers(dev, intel_dp,
                                                      &power_seq);
 
+       /*
+        * Even vdd force doesn't work until we've made
+        * the power sequencer lock in on the port.
+        */
+       DRM_DEBUG_KMS("kicking pipe %c power sequencer\n",
+                     pipe_name(intel_dp->pipe));
+
+       vlv_power_sequencer_kick(intel_dp, intel_dp->pipe);
+
        return intel_dp->pipe;
 }
 
@@ -370,6 +424,9 @@ vlv_initial_power_sequencer_setup(struct intel_dp *intel_dp)
        intel_dp_init_panel_power_sequencer(dev, intel_dp, &power_seq);
        intel_dp_init_panel_power_sequencer_registers(dev, intel_dp,
                                                      &power_seq);
+
+       /* kick it just in case someone left it in a stuck state */
+       vlv_power_sequencer_kick(intel_dp, intel_dp->pipe);
 }
 
 static u32 _pp_ctrl_reg(struct intel_dp *intel_dp)
-- 
1.8.5.5

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