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

[Pandiyan, Dhinakaran]

On Tue, 2017-05-09 at 16:39 -0700, Puthikorn Voravootivat wrote:
> > How is backlight enabled in this case?
> Using eDP BL_ENABLE pin


Sure, but I am not seeing how this falls back to one of the
[bxt,lpt]_enable_backlight() functions in intel_panel.c. Apologies if I
am missing something very obvious.

If intel_dp_aux_init_backlight_funcs() returned -ENODEV, then one of the
platform specific PWM enable callbacks would be called. But in this
case, dp_aux_enable_backlight() just returns without doing anything.


-DK
> 
> 
> 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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