[Intel-gfx] [v3] drm/i915/pps: improve eDP power on flow

[Lee Shawn C]

After i915 dirver initialized, a panel power off cycle delay
always append before turn eDP on. If eDP display did not
power on before. With this change, power off duration might
longer than power cycle delay. So driver can save power cycle
delay to speed up driver initialization time.

v2: fix commit messages
v3: refine panel_power_off_time default value and modify
    commit messages

Cc: Shankar Uma <uma.shankar at intel.com>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Lee Shawn C <shawn.c.lee at intel.com>
---
 drivers/gpu/drm/i915/display/intel_pps.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_pps.c b/drivers/gpu/drm/i915/display/intel_pps.c
index 21944f5bf3a8..a394bb1c92d0 100644
--- a/drivers/gpu/drm/i915/display/intel_pps.c
+++ b/drivers/gpu/drm/i915/display/intel_pps.c
@@ -1098,7 +1098,7 @@ bool intel_pps_have_panel_power_or_vdd(struct intel_dp *intel_dp)
 
 static void pps_init_timestamps(struct intel_dp *intel_dp)
 {
-	intel_dp->pps.panel_power_off_time = ktime_get_boottime();
+	intel_dp->pps.panel_power_off_time = 0;
 	intel_dp->pps.last_power_on = jiffies;
 	intel_dp->pps.last_backlight_off = jiffies;
 }
-- 
2.17.1