[Intel-gfx] [PATCH] drm/i915/vlv: T12 eDP panel timing enforcement during reboot

[Jani Nikula]

From: Clint Taylor <Clinton.A.Taylor at 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.

Ver4: Minor issue changes

Signed-off-by: Clint Taylor <clinton.a.taylor at intel.com>
[Jani: rebased on current -nightly.]
Signed-off-by: Jani Nikula <jani.nikula at intel.com>

---

I ended up doing the rebase myself, but I'd like to have a quick review
before pushing.

Thanks,
Jani.
---
 drivers/gpu/drm/i915/intel_dp.c  | 40 ++++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h |  2 ++
 2 files changed, 42 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index b5ec48913b47..f0d23c435cf6 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 +338,36 @@ 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 drm_device *dev = intel_dp_to_dev(intel_dp);
+	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 +3817,10 @@ 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 +4389,10 @@ 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 5f7c7bd94d90..87d1715db21d 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -541,6 +541,8 @@ 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;
 
-- 
2.0.0