Re: [PATCH] drm/i915: Refine eDP aux backlight enable sequence.

[Jani Nikula <jani.nikula@intel.com>]

On Thu, 13 Jun 2019, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Wed, Jun 12, 2019 at 10:47:22PM -0700, Lee, Shawn C wrote:
>> Modify aux backlight enable sequence just like what we
>> did for genernal eDP panel.
>> 1. Setup PWM freq and brightness level before enable display backlight.
>> 2. Add T8 (valid data to backlight enable) delay.
>
> If we respect the on_delay shouldn't we then respect the off_delay too?
>
> In which case I suggest two patches:
> 1. swaap the enable vs. set_brightness order
> 2. add the on/off delays

The aux backlight functions are called via the same hooks as everything
in intel_panel.c, which do not have delays (they're all on the calling
side in intel_dp.c) so I'm confused why these would require the delays.

BR,
Jani.



>
>> 
>> Cc: Jani Nikula <jani.nikula@intel.com>
>> Cc: Jose Roberto de Souza <jose.souza@intel.com>
>> Cc: Cooper Chiou <cooper.chiou@intel.com>
>> 
>> Signed-off-by: Lee, Shawn C <shawn.c.lee@intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
>> index 7ded95a334db..c112e0b930de 100644
>> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
>> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
>> @@ -216,8 +216,12 @@ static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_st
>>  		}
>>  	}
>>  
>> -	set_aux_backlight_enable(intel_dp, true);
>>  	intel_dp_aux_set_backlight(conn_state, connector->panel.backlight.level);
>> +
>> +	wait_remaining_ms_from_jiffies(intel_dp->last_power_on,
>> +				       intel_dp->backlight_on_delay);
>> +
>> +	set_aux_backlight_enable(intel_dp, true);
>>  }
>>  
>>  static void intel_dp_aux_disable_backlight(const struct drm_connector_state *old_conn_state)
>> -- 
>> 2.7.4
>> 
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-- 
Jani Nikula, Intel Open Source Graphics Center
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