From: Clint Taylor <clinton.a.tay...@intel.com>

The panel power sequencer on vlv doesn't appear to accept changes to its
T12 power down duration during warm reboots. This change forces a delay
for warm reboots to the T12 panel timing as defined in the VBT table for
the connected panel.

Ver2: removed redundant pr_crit(), commented magic value for pp_div_reg

Ver3: moved SYS_RESTART check earlier, new name for pp_div.

Signed-off-by: Clint Taylor <clinton.a.tay...@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.v...@intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c  | 42 ++++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h |  2 ++
 2 files changed, 44 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index b5ec489..ece8f28 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -28,6 +28,8 @@
 #include <linux/i2c.h>
 #include <linux/slab.h>
 #include <linux/export.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
 #include <drm/drmP.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
@@ -336,6 +338,38 @@ static u32 _pp_stat_reg(struct intel_dp *intel_dp)
                return VLV_PIPE_PP_STATUS(vlv_power_sequencer_pipe(intel_dp));
 }
 
+/* Reboot notifier handler to shutdown panel power to guarantee T12 timing */
+static int edp_notify_handler(struct notifier_block *this, unsigned long code,
+                                                         void *unused)
+{
+       struct intel_dp *intel_dp = container_of(this, typeof(* intel_dp),
+                                                edp_notifier);
+       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;
+       u32 pp_div;
+       u32 pp_ctrl_reg, pp_div_reg;
+       enum pipe pipe = vlv_power_sequencer_pipe(intel_dp);
+
+       if ((!is_edp(intel_dp)) &&
+           (code != SYS_RESTART ))
+               return 0;
+
+       if (IS_VALLEYVIEW(dev)) {
+               pp_ctrl_reg = VLV_PIPE_PP_CONTROL(pipe);
+               pp_div_reg  = VLV_PIPE_PP_DIVISOR(pipe);
+               pp_div = I915_READ(VLV_PIPE_PP_DIVISOR(pipe));
+               pp_div &= PP_REFERENCE_DIVIDER_MASK;
+
+               /* 0x1F write to PP_DIV_REG sets max cycle delay */
+               I915_WRITE(pp_div_reg , pp_div | 0x1F);
+               I915_WRITE(pp_ctrl_reg,
+                          PANEL_UNLOCK_REGS | PANEL_POWER_OFF);
+               msleep(intel_dp->panel_power_cycle_delay);
+       }
+       return 0;
+}
+
 static bool edp_have_panel_power(struct intel_dp *intel_dp)
 {
        struct drm_device *dev = intel_dp_to_dev(intel_dp);
@@ -3785,6 +3819,10 @@ void intel_dp_encoder_destroy(struct drm_encoder 
*encoder)
                drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
                edp_panel_vdd_off_sync(intel_dp);
                drm_modeset_unlock(&dev->mode_config.connection_mutex);
+               if (intel_dp->edp_notifier.notifier_call) {
+                       unregister_reboot_notifier(&intel_dp->edp_notifier);
+                       intel_dp->edp_notifier.notifier_call = NULL;
+               }
        }
        kfree(intel_dig_port);
 }
@@ -4353,6 +4391,10 @@ intel_dp_init_connector(struct intel_digital_port 
*intel_dig_port,
        if (is_edp(intel_dp)) {
                intel_dp_init_panel_power_timestamps(intel_dp);
                intel_dp_init_panel_power_sequencer(dev, intel_dp, &power_seq);
+               if (IS_VALLEYVIEW(dev)) {
+                       intel_dp->edp_notifier.notifier_call = 
edp_notify_handler;
+                       register_reboot_notifier(&intel_dp->edp_notifier);
+               }
        }
 
        intel_dp_aux_init(intel_dp, intel_connector);
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 7b4d743..c52e879 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -542,6 +542,8 @@ struct intel_dp {
        unsigned long last_power_cycle;
        unsigned long last_power_on;
        unsigned long last_backlight_off;
+       struct notifier_block  edp_notifier;
+
        bool use_tps3;
        struct intel_connector *attached_connector;
 
-- 
1.9.0

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