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.
>
>
> -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;
>>
>>
>>
>>
>> _______________________________________________
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>> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
--
Jani Nikula, Intel Open Source Technology Center
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