[Intel-gfx] [PATCH v5 3/9] drm/i915: Drop AUX backlight enable check for backlight control

[Puthikorn Voravootivat]

> How is backlight enabled in this case?
Using eDP BL_ENABLE pin

On Sat, May 6, 2017 at 1:59 AM, Pandiyan, Dhinakaran <
dhinakaran.pandiyan at intel.com> wrote:

> On Wed, 2017-05-03 at 17:28 -0700, Puthikorn Voravootivat wrote:
> > There are some panel that
> > (1) does not support display backlight enable via AUX
> > (2) support display backlight adjustment via AUX
> > (3) support display backlight enable via eDP BL_ENABLE pin
> >
> > The current driver required that (1) must be support to enable (2).
> > This patch drops that requirement.
> >
> > Signed-off-by: Puthikorn Voravootivat <puthik at chromium.org>
> > ---
> >  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 5 ++++-
> >  1 file changed, 4 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 ad8560c5f689..5b83c9737644 100644
> > --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> > +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> > @@ -28,6 +28,10 @@ static void set_aux_backlight_enable(struct intel_dp
> *intel_dp, bool enable)
> >  {
> >       uint8_t reg_val = 0;
> >
> > +       /* Early return when display use other mechanism to enable
> backlight. */
> > +     if (!(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP))
> > +             return;
> > +
>
> How is backlight enabled in this case?
>
> -DK
>
> >       if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_
> REGISTER,
> >                             &reg_val) < 0) {
> >               DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
> > @@ -164,7 +168,6 @@ intel_dp_aux_display_control_capable(struct
> intel_connector *connector)
> >        * the panel can support backlight control over the aux channel
> >        */
> >       if ((intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP)
> &&
> > -         (intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
> >           (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP))
> {
> >               DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
> >               return true;
>
>
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