Re: [PATCH 7/8] drm/i915/backlight: Provide clear description on how backlight level is controlled

["Murthy, Arun R" <arun.r.murthy@intel.com>]

On 24-02-2026 08:50, Kandpal, Suraj wrote:
>> Subject: Re: [PATCH 7/8] drm/i915/backlight: Provide clear description on how
>> backlight level is controlled
>>
>> On 20-02-2026 10:32, Suraj Kandpal wrote:
>>> Currently it takes us multiple log prints to arrive at the conclusion
>>> on how we are actually controlling backlight level. Make the logging
>>> concise.
>>>
>>> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
>>> ---
>>>    .../drm/i915/display/intel_dp_aux_backlight.c | 19 ++++++++++++++-----
>>>    1 file changed, 14 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
>>> b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
>>> index 043c9aef2ea6..aac6cdb5b69b 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
>>> @@ -368,6 +368,16 @@ static const char *dpcd_vs_pwm_str(bool aux)
>>>    	return aux ? "DPCD" : "PWM";
>>>    }
>>>
>>> +static const char *backlight_unit_str(struct intel_panel *panel) {
>>> +	if (panel->backlight.edp.vesa.info.luminance_set)
>>> +		return "NITS";
>>> +	else if (panel->backlight.edp.vesa.info.aux_set)
>>> +		return "Brightness %";
>> Should this be AUX Brightness?
>> So that it calls out its AUX based DPCD backlight control.
> Actually where this is called has the line
> "AUX VESA backlight level is controlled through %s using %s values\n"
> Here we return the unit value we use to control brightness

Sorry missed that, so with having AUX backlight already, this proposed 
change doesnt make much sense.

Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>

Thanks and Regards,
Arun R Murthy
-------------------

> Regards,
> Suraj Kandpal
>
>>> +	else
>>> +		return "PWM";
>>> +}
>>> +
>>>    static void
>>>    intel_dp_aux_write_panel_luminance_override(struct intel_connector
>> *connector)
>>>    {
>>> @@ -542,9 +552,11 @@ static int
>> intel_dp_aux_vesa_setup_backlight(struct intel_connector *connector,
>>>    		    dpcd_vs_pwm_str(panel-
>>> backlight.edp.vesa.info.aux_enable ||
>>>    				    panel-
>>> backlight.edp.vesa.info.luminance_set));
>>>    	drm_dbg_kms(display->drm,
>>> -		    "[CONNECTOR:%d:%s] AUX VESA backlight level is
>> controlled through %s\n",
>>> +		    "[CONNECTOR:%d:%s] AUX VESA backlight level is
>> controlled
>>> +through %s using %s values\n",
>>>    		    connector->base.base.id, connector->base.name,
>>> -		    dpcd_vs_pwm_str(panel-
>>> backlight.edp.vesa.info.aux_set));
>>> +		    dpcd_vs_pwm_str(panel->backlight.edp.vesa.info.aux_set
>> ||
>>> +				    panel-
>>> backlight.edp.vesa.info.luminance_set),
>>> +		    backlight_unit_str(panel));
>>>
>>>    	if (!panel->backlight.edp.vesa.info.aux_set ||
>>>    	    !panel->backlight.edp.vesa.info.aux_enable) { @@ -569,9 +581,6
>>> @@ static int intel_dp_aux_vesa_setup_backlight(struct intel_connector
>> *connector,
>>>    		panel->backlight.enabled = panel->backlight.level != 0;
>>>    		if (!panel->backlight.level)
>>>    			panel->backlight.level = panel->backlight.max;
>>> -		drm_dbg_kms(display->drm,
>>> -			    "[CONNECTOR:%d:%s] AUX VESA Nits backlight
>> level is controlled through DPCD\n",
>>> -			    connector->base.base.id, connector->base.name);
>>>    	} else if (panel->backlight.edp.vesa.info.aux_set) {
>>>    		panel->backlight.max = panel->backlight.edp.vesa.info.max;
>>>    		panel->backlight.min = 0;