| Message ID | 1561087486-19339-1-git-send-email-shawn.c.lee@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915: Refine eDP aux backlight enable/disable sequence | expand |
On Thu, 20 Jun 2019, Lee Shawn C <shawn.c.lee@intel.com> wrote: > Modify aux backlight enable/disable sequence just like what we > did for genernal eDP panel. > 1. Setup PWM freq and brightness level before enable display backlight. > 2. Set PWM to 0 after backlight enable was off. It took me a while to realize why we do this in this order. eDP v1.4b says about DPCD addresses 00722h-00723h i.e. EDP_BACKLIGHT_BRIGHTNESS MSB and LSB: """ Writes are ignored if: [...] - BACKLIGHT_ENABLE bit in the EDP_DISPLAY_CONTROL register (DPCD Address 00720h, bit 0) is cleared to 0" """ i.e. per the spec this change makes the brightness updates no-ops. Do you have a panel where this patch makes a difference? BR, Jani. > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> > Cc: Jani Nikula <jani.nikula@intel.com> > Cc: Jose Roberto de Souza <jose.souza@intel.com> > Cc: Cooper Chiou <cooper.chiou@intel.com> > > Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com> > --- > drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c > index 6b0b73479fb8..bbc579734238 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c > @@ -216,13 +216,14 @@ static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_st > } > } > > - set_aux_backlight_enable(intel_dp, true); > intel_dp_aux_set_backlight(conn_state, connector->panel.backlight.level); > + set_aux_backlight_enable(intel_dp, true); > } > > static void intel_dp_aux_disable_backlight(const struct drm_connector_state *old_conn_state) > { > set_aux_backlight_enable(enc_to_intel_dp(old_conn_state->best_encoder), false); > + intel_dp_aux_set_backlight(old_conn_state, 0); > } > > static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
On Tue, 25 Jun 2019, Jani Nikula <jani.nikula@intel.com> wrote: >On Thu, 20 Jun 2019, Lee Shawn C <shawn.c.lee@intel.com> wrote: >> Modify aux backlight enable/disable sequence just like what we did for >> genernal eDP panel. >> 1. Setup PWM freq and brightness level before enable display backlight. >> 2. Set PWM to 0 after backlight enable was off. > >It took me a while to realize why we do this in this order. > >eDP v1.4b says about DPCD addresses 00722h-00723h i.e. EDP_BACKLIGHT_BRIGHTNESS MSB and LSB: > >""" >Writes are ignored if: > >[...] > >- BACKLIGHT_ENABLE bit in the EDP_DISPLAY_CONTROL register (DPCD Address > 00720h, bit 0) is cleared to 0" >""" > >i.e. per the spec this change makes the brightness updates no-ops. > >Do you have a panel where this patch makes a difference? > >BR, >Jani. > What you say is correct. According to spec, write EDP_BACKLIGHT_BRIGHTNESS does not affect if BACKLIGHT_ENABLE already be off. Backlight enable always turn off before stop PWM output when used general eDP backlight (from SOC) control. But AUX backlight control is a little different. I will update this patch and remove "Set PWM to 0". >> >> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> >> Cc: Jani Nikula <jani.nikula@intel.com> >> Cc: Jose Roberto de Souza <jose.souza@intel.com> >> Cc: Cooper Chiou <cooper.chiou@intel.com> >> >> Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com> >> --- >> drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c >> b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c >> index 6b0b73479fb8..bbc579734238 100644 >> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c >> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c >> @@ -216,13 +216,14 @@ static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_st >> } >> } >> >> - set_aux_backlight_enable(intel_dp, true); >> intel_dp_aux_set_backlight(conn_state, >> connector->panel.backlight.level); >> + set_aux_backlight_enable(intel_dp, true); >> } >> >> static void intel_dp_aux_disable_backlight(const struct >> drm_connector_state *old_conn_state) { >> >> set_aux_backlight_enable(enc_to_intel_dp(old_conn_state->best_encoder) >> , false); >> + intel_dp_aux_set_backlight(old_conn_state, 0); >> } >> >> static int intel_dp_aux_setup_backlight(struct intel_connector >> *connector, > >-- >Jani Nikula, Intel Open Source Graphics Center >
On Tue, 25 Jun 2019, "Lee, Shawn C" <shawn.c.lee@intel.com> wrote: > On Tue, 25 Jun 2019, Jani Nikula <jani.nikula@intel.com> wrote: >>On Thu, 20 Jun 2019, Lee Shawn C <shawn.c.lee@intel.com> wrote: >>> Modify aux backlight enable/disable sequence just like what we did for >>> genernal eDP panel. >>> 1. Setup PWM freq and brightness level before enable display backlight. >>> 2. Set PWM to 0 after backlight enable was off. >> >>It took me a while to realize why we do this in this order. >> >>eDP v1.4b says about DPCD addresses 00722h-00723h i.e. EDP_BACKLIGHT_BRIGHTNESS MSB and LSB: >> >>""" >>Writes are ignored if: >> >>[...] >> >>- BACKLIGHT_ENABLE bit in the EDP_DISPLAY_CONTROL register (DPCD Address >> 00720h, bit 0) is cleared to 0" >>""" >> >>i.e. per the spec this change makes the brightness updates no-ops. >> >>Do you have a panel where this patch makes a difference? >> >>BR, >>Jani. >> > > What you say is correct. According to spec, write EDP_BACKLIGHT_BRIGHTNESS does not affect > if BACKLIGHT_ENABLE already be off. > > Backlight enable always turn off before stop PWM output when used general eDP backlight (from SOC) control. > But AUX backlight control is a little different. I will update this patch and remove "Set PWM to 0". AFAICT the only thing you can do, really, is calling intel_dp_aux_set_backlight(old_conn_state, 0); *before* set_aux_backlight_enable(enc_to_intel_dp(old_conn_state->best_encoder), false); in intel_dp_aux_disable_backlight(). BR, Jani. > >>> >>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> >>> Cc: Jani Nikula <jani.nikula@intel.com> >>> Cc: Jose Roberto de Souza <jose.souza@intel.com> >>> Cc: Cooper Chiou <cooper.chiou@intel.com> >>> >>> Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com> >>> --- >>> drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 3 ++- >>> 1 file changed, 2 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c >>> b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c >>> index 6b0b73479fb8..bbc579734238 100644 >>> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c >>> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c >>> @@ -216,13 +216,14 @@ static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_st >>> } >>> } >>> >>> - set_aux_backlight_enable(intel_dp, true); >>> intel_dp_aux_set_backlight(conn_state, >>> connector->panel.backlight.level); >>> + set_aux_backlight_enable(intel_dp, true); >>> } >>> >>> static void intel_dp_aux_disable_backlight(const struct >>> drm_connector_state *old_conn_state) { >>> >>> set_aux_backlight_enable(enc_to_intel_dp(old_conn_state->best_encoder) >>> , false); >>> + intel_dp_aux_set_backlight(old_conn_state, 0); >>> } >>> >>> static int intel_dp_aux_setup_backlight(struct intel_connector >>> *connector, >> >>-- >>Jani Nikula, Intel Open Source Graphics Center >>
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c index 6b0b73479fb8..bbc579734238 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -216,13 +216,14 @@ static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_st } } - set_aux_backlight_enable(intel_dp, true); intel_dp_aux_set_backlight(conn_state, connector->panel.backlight.level); + set_aux_backlight_enable(intel_dp, true); } static void intel_dp_aux_disable_backlight(const struct drm_connector_state *old_conn_state) { set_aux_backlight_enable(enc_to_intel_dp(old_conn_state->best_encoder), false); + intel_dp_aux_set_backlight(old_conn_state, 0); } static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
Modify aux backlight enable/disable sequence just like what we did for genernal eDP panel. 1. Setup PWM freq and brightness level before enable display backlight. 2. Set PWM to 0 after backlight enable was off. Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Jose Roberto de Souza <jose.souza@intel.com> Cc: Cooper Chiou <cooper.chiou@intel.com> Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com> --- drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)