On Tue, May 2, 2017 at 8:00 PM, Pandiyan, Dhinakaran < dhinakaran.pandi...@intel.com> wrote:
> On Tue, 2017-04-18 at 16:48 -0700, Puthikorn Voravootivat wrote: > > This patch enables dynamic backlight by default for eDP > > panel that supports this feature via DPCD register and > > set minimum / maximum brightness to 0% and 100% of the > > normal brightness. > > > What does dynamic backlight do? I am trying to understand what allowing > 0% minimum brightness means. > > Display will make backlight dimmer when content shown on screen is darker. See https://www.ecnmag.com/article/2010/04/content-adaptive-lcd-backlight-control > > > > > Signed-off-by: Puthikorn Voravootivat <put...@chromium.org> > > --- > > drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 31 > +++++++++++++++++++++++---- > > 1 file changed, 27 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c > b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c > > index f06c8381c74e..ae1b6fe67feb 100644 > > --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c > > +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c > > @@ -97,10 +97,24 @@ intel_dp_aux_set_backlight(struct intel_connector > *connector, u32 level) > > } > > } > > > > +/* > > + * Set minimum / maximum dynamic brightness percentage. This value is > expressed > > + * as the percentage of normal brightness in 5% increments. > > + */ > > +static void > > +intel_dp_aux_set_dynamic_backlight_percent(struct intel_dp *intel_dp, > > + u32 min, u32 max) > > +{ > > + u8 dbc[] = { DIV_ROUND_CLOSEST(min, 5), DIV_ROUND_CLOSEST(max, 5) > }; > > + drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_DBC_MINIMUM_BRIGHTNESS_ > SET, > > + dbc, sizeof(dbc)); > > +} > > + > > static void intel_dp_aux_enable_backlight(struct intel_connector > *connector) > > { > > struct intel_dp *intel_dp = enc_to_intel_dp(&connector-> > encoder->base); > > uint8_t dpcd_buf = 0; > > + uint8_t new_dpcd_buf = 0; > > uint8_t edp_backlight_mode = 0; > > > > set_aux_backlight_enable(intel_dp, true); > > @@ -110,16 +124,15 @@ static void intel_dp_aux_enable_backlight(struct > intel_connector *connector) > > return; > > } > > > > + new_dpcd_buf = dpcd_buf; > > edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_ > MASK; > > > > switch (edp_backlight_mode) { > > case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM: > > case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET: > > case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT: > > - dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK; > > - dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD; > > - drm_dp_dpcd_writeb(&intel_dp->aux, > > - DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf); > > + new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK; > > + new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD; > > break; > > > > /* Do nothing when it is already DPCD mode */ > > @@ -127,6 +140,16 @@ static void intel_dp_aux_enable_backlight(struct > intel_connector *connector) > > default: > > break; > > } > > > Still need a switch here? You are setting mode as > DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD for all four values of mode. > > > > > + > > + if (intel_dp->edp_dpcd[2] & DP_EDP_DYNAMIC_BACKLIGHT_CAP) { > > + new_dpcd_buf |= DP_EDP_DYNAMIC_BACKLIGHT_ENABLE; > > + intel_dp_aux_set_dynamic_backlight_percent(intel_dp, 0, > 100); > > + } > > Should enabling dynamic backlight control be logged in debug messages? > Could be useful in case this turns out to be buggy. > Sure > > -DK > > > + > > + if (new_dpcd_buf != dpcd_buf) { > > + drm_dp_dpcd_writeb(&intel_dp->aux, > > + DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf); > > + } > > } > > > > static void intel_dp_aux_disable_backlight(struct intel_connector > *connector) > >
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