RE: drm/i915/backlight: Remove DP_EDP_BACKLIGHT_AUX_ENABLE_CAP check for DPCD backlight

> Subject: RE: drm/i915/backlight: Remove
> DP_EDP_BACKLIGHT_AUX_ENABLE_CAP check for DPCD backlight
> 
> > Subject: Re: drm/i915/backlight: Remove
> > DP_EDP_BACKLIGHT_AUX_ENABLE_CAP check for DPCD backlight
> >
> > On Thu, 16 Jul 2026, Suraj Kandpal wrote:
> > > Turns out Some panels allow only backlight AUX based backlight
> >
> > nits:
> > s/Some/some/
> > s/backlight AUX/AUX/
> >
> > > by just setting the DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP and
> not
> > > setting the DP_EDP_BACKLIGHT_AUX_ENABLE_CAP.
> > > If we make DP_EDP_BACKLIGHT_AUX_ENABLE_CAP a necessity for AUX
> based
> > > DPCD backlight these panels loose the ability to manipulate
> > > backlight via AUX, specially ones with no PWM controller.
> >
> > maybe: s/specially/especially/
> >
> > > Remove this check from function so that panels who do not advertise
> > > DP_EDP_BACKLIGHT_AUX_ENABLE_CAP but advertise
> > > DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP are able to manipulate
> > > backlight again.
> > >
> > > Fixes: ed8be780bdbc ("drm/i915/backlight: Fix VESA backlight
> > > possible check condition")
> > > Closes:
> > > https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/16507
> > > Signed-off-by: Suraj Kandpal <[email protected]>
> >
> > > ---
> > > drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 3 +--
> > > 1 file changed, 1 insertion(+), 2 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 7a6c07f6aaeb..83245cb738e5 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> > > @@ -619,8 +619,7 @@ check_if_vesa_backlight_possible(struct intel_dp
> > *intel_dp)
> > > 	 * Since we only support Fully AUX Based VESA Backlight interface
> > > make
> > sure
> > > 	 * backlight enable is possible via AUX along with backlight adjustment
> > > 	 */
> >
> > Wondering if the comment above needs any adjustment?
> 
> You are right this comment will need to be removed  now
> 
> >
> > Either way:
> > Reviewed-by: Michał Grzelak <[email protected]>
> >
> 
> Thanks for the reviews,
> Pushed to din with above mentioned changes
> 
> Regards,
> Suraj Kandpal
> 

Cc: [email protected]
> > BR,
> > Michał
> >
> > > -	if (!(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP
> > &&
> > > -	      intel_dp->edp_dpcd[2] &
> > DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP))
> > > +	if (!(intel_dp->edp_dpcd[2] &
> > > +DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP))
> > > 		return false;
> > >
> > > 	ret = drm_dp_dpcd_read_byte(&intel_dp->aux,
> > > DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN, &bit_min);
> > >