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

[Lee, Shawn C]

On Thursday, November 3, 2022 7:00 PM, Jani Nikula <jani.nikula at linux.intel.com> wrote:
>On Thu, 03 Nov 2022, Lee Shawn C <shawn.c.lee at intel.com> wrote:
>> 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;
>
>So this is just copy-paste from [1] where we discuss the problems with this approach, specifically module reload ignoring the power off time.
>Why would you post this without even mentioning the problem?
>

OK, we will stop commit any patch until we have proper solution. Could you please share your opinion about next step? Thanks!

Best regards,
Shawn

>
>BR,
>Jani.
>
>
>[1] https://gitlab.freedesktop.org/drm/intel/-/issues/7417#note_1619118
>
>>  	intel_dp->pps.last_power_on = jiffies;
>>  	intel_dp->pps.last_backlight_off = jiffies;  }
>
>--
>Jani Nikula, Intel Open Source Graphics Center