From: Zhang Ning <ning.a.zhang@xxxxxxxxx>
power on an eDP panel requests eDP panal fully powered off.
need to wait t11_t12 after LCDVCC is off. usually t12 is 500ms.
code, intel_dp.c, func edp_panel_vdd_on, line 2010:
if (!edp_have_panel_power(intel_dp))
wait_panel_power_cycle(intel_dp);
translate to human readable:
if panel is off; then wait.
the wait time is (t11_t12 - power_off_duration).
power_off_duration = (now_time - last_off_timestamp)
when (t10_t12 > power_off_duration), a wait is requested.
otherwise not needed.
for coldboot, panel is powered off, not powered on.
so last_off_timestamp for coldboot should be 0.
but in code, this value is set to i915 module initial timestamp,
by:
static void intel_dp_init_panel_power_timestamps(struct intel_dp
*intel_dp)
{
intel_dp->panel_power_off_time = ktime_get_boottime();
intel_dp->last_power_on = jiffies;
intel_dp->last_backlight_off = jiffies;
}
this is not real last_off_timestamp, and make i915 driver wait unnecessarily.
to make i915 initial faster, set panel_power_off_time to (ktime_t){.tv64
= 0}
actully saves 200ms for coldboot.
Signed-off-by: Zhang Ning <ning.a.zhang@xxxxxxxxx>
Reviewed-off-by: Zhang, Baoli <baoli.zhang@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 1193202766a2..9b985768ead6 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -5373,7 +5373,7 @@ intel_dp_add_properties(struct intel_dp *intel_dp, struct drm_connector *connect
static void intel_dp_init_panel_power_timestamps(struct intel_dp *intel_dp)
{
- intel_dp->panel_power_off_time = ktime_get_boottime();
+ intel_dp->panel_power_off_time = ktime_set(0, 0);
intel_dp->last_power_on = jiffies;
intel_dp->last_backlight_off = jiffies;
}
--
2.18.0
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