On Wed, 2017-05-10 at 13:05 +0300, Jani Nikula wrote:
> On Wed, 10 May 2017, "Pandiyan, Dhinakaran" <dhinakaran.pandiyan@xxxxxxxxx> wrote:
> > 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.
>
> The eDP BL_ENABLE pin (in the physical eDP connector) is controlled by
> the panel power sequencer, independent from the PWM control. See
> intel_edp_backlight_* functions in intel_dp.c.
>
> BR,
> Jani.
>
>
Ah! Thanks, that makes sense. The naming is a bit confusing though. The
_enable_backlight() functions in intel_panel.c don't enable backlight
but enable PWM.
> >
> >
> > -DK
> >>
> >>
> >> On Sat, May 6, 2017 at 1:59 AM, Pandiyan, Dhinakaran
> >> <dhinakaran.pandiyan@xxxxxxxxx> 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@xxxxxxxxxxxx>
> >> > ---
> >> > 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,
> >> > ®_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;
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> Intel-gfx mailing list
> >> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> >> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> >
>
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