[PATCH 10/13] drm/dp: Enable backlight control using luminance

[Kandpal, Suraj]

> -----Original Message-----
> From: Murthy, Arun R <arun.r.murthy at intel.com>
> Sent: Friday, June 20, 2025 10:17 AM
> To: Kandpal, Suraj <suraj.kandpal at intel.com>;
> nouveau at lists.freedesktop.org; dri-devel at lists.freedesktop.org; intel-
> xe at lists.freedesktop.org; intel-gfx at lists.freedesktop.org
> Cc: Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>
> Subject: RE: [PATCH 10/13] drm/dp: Enable backlight control using luminance
> 
> > -----Original Message-----
> > From: Kandpal, Suraj <suraj.kandpal at intel.com>
> > Sent: Monday, April 14, 2025 9:47 AM
> > To: nouveau at lists.freedesktop.org; dri-devel at lists.freedesktop.org;
> > intel- xe at lists.freedesktop.org; intel-gfx at lists.freedesktop.org
> > Cc: Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>; Murthy, Arun R
> > <arun.r.murthy at intel.com>; Kandpal, Suraj <suraj.kandpal at intel.com>
> > Subject: [PATCH 10/13] drm/dp: Enable backlight control using
> > luminance
> >
> > Add flag to enable brightness control via luminance value when
> > enabling edp backlight.
> >
> > Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> > ---
> >  drivers/gpu/drm/display/drm_dp_helper.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
> > b/drivers/gpu/drm/display/drm_dp_helper.c
> > index 0421b2ed9bd4..4e2caba8311a 100644
> > --- a/drivers/gpu/drm/display/drm_dp_helper.c
> > +++ b/drivers/gpu/drm/display/drm_dp_helper.c
> > @@ -4030,6 +4030,9 @@ int drm_edp_backlight_enable(struct
> drm_dp_aux
> > *aux, const struct drm_edp_backli
> >  	else
> >  		dpcd_buf = DP_EDP_BACKLIGHT_CONTROL_MODE_PWM;
> >
> > +	if (bl->luminance_set)
> > +		dpcd_buf |=
> DP_EDP_PANEL_LUMINANCE_CONTROL_ENABLE;
> Can the backlight control by luminance be used along with PWM or AUX ctl?
> 

It does work.

> Thanks and Regards,
> Arun R Murthy
> -------------------
> > +
> >  	if (bl->pwmgen_bit_count) {
> >  		ret = drm_dp_dpcd_write_byte(aux,
> > DP_EDP_PWMGEN_BIT_COUNT, bl->pwmgen_bit_count);
> >  		if (ret < 0)
> > --
> > 2.34.1