[Intel-gfx] [PATCH] drm/i915/dp: Backlight PWM enable before BL Enable assert

[clinton.a.taylor at intel.com]

From: Clint Taylor <clinton.a.taylor at intel.com>

Backlight on delay uses PWM enable time to seperate PWM to
backlight enable assert. Previous time difference used timing
from VDD enable which occur several seconds before resulting
in PWM starting 5ms after backlight enable. Changes to backlight
 duty cycle take affect at the end of the current PWM cycle.
Measured time for the PWM cycle is 5ms. 5 additional ms must be
added to the backlight_on_delay to get correct VBT timing of
PWM to backlight enable assert.

Change-Id: I484999a597fd84dacf4cf99a168ec9ba4bb6ff11
Signed-off-by: Clint Taylor <clinton.a.taylor at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c  | 6 ++++--
 drivers/gpu/drm/i915/intel_drv.h | 1 +
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index e5ada4f..c59ccdb 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1141,7 +1141,7 @@ static void wait_panel_power_cycle(struct intel_dp *intel_dp)
 
 static void wait_backlight_on(struct intel_dp *intel_dp)
 {
-	wait_remaining_ms_from_jiffies(intel_dp->last_power_on,
+	wait_remaining_ms_from_jiffies(intel_dp->last_backlight_on,
 				       intel_dp->backlight_on_delay);
 }
 
@@ -1398,6 +1398,7 @@ void intel_edp_backlight_on(struct intel_dp *intel_dp)
 	DRM_DEBUG_KMS("\n");
 
 	intel_panel_enable_backlight(intel_dp->attached_connector);
+	intel_dp->last_backlight_on = jiffies;
 
 	/*
 	 * If we enable the backlight right away following a panel power
@@ -4243,9 +4244,10 @@ intel_dp_init_panel_power_sequencer(struct drm_device *dev,
 	assign_final(t11_t12);
 #undef assign_final
 
+#define PWM_CYCLE_DELAY 5
 #define get_delay(field)	(DIV_ROUND_UP(final.field, 10))
 	intel_dp->panel_power_up_delay = get_delay(t1_t3);
-	intel_dp->backlight_on_delay = get_delay(t8);
+	intel_dp->backlight_on_delay = get_delay(t8) + PWM_CYCLE_DELAY;
 	intel_dp->backlight_off_delay = get_delay(t9);
 	intel_dp->panel_power_down_delay = get_delay(t10);
 	intel_dp->panel_power_cycle_delay = get_delay(t11_t12);
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 3abc915..ad6fcc1 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -556,6 +556,7 @@ struct intel_dp {
 	bool want_panel_vdd;
 	unsigned long last_power_cycle;
 	unsigned long last_power_on;
+	unsigned long last_backlight_on;
 	unsigned long last_backlight_off;
 
 	struct notifier_block edp_notifier;
-- 
1.8.3.2