Re: [PATCH 1/2] drm/i915/backlight: handle enabled but zero duty cycle at module load

Jani Nikula
2016-08-25T11:27:07Z

On Tue, 23 Aug 2016, Maarten Lankhorst <maarten.lankhorst@linux.intel.com> wrote:
> From: Jani Nikula <jani.nikula@intel.com>
>
> Don't consider enabled but zero duty cycle backlight disabled. Clamp
> level between min and max for sanity.
>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>

I think this is the right thing to do.

In the future, perhaps we'll want to check for !enabled, and actually
enable the backlight too if backlight is present and the crtc is active.

Please just push this, and we'll see what happens.

BR,
Jani.

> ---
> drivers/gpu/drm/i915/intel_panel.c | 40 +++++++++++++++++++++++---------------
> 1 file changed, 24 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index 96c65d77e886..c10e9b0405e8 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -1430,10 +1430,11 @@ static int lpt_setup_backlight(struct intel_connector *connector, enum pipe unus
> panel->backlight.min = get_backlight_min_vbt(connector);
>
> val = lpt_get_backlight(connector);
> - panel->backlight.level = intel_panel_compute_brightness(connector, val);
> + val = intel_panel_compute_brightness(connector, val);
> + panel->backlight.level = clamp(val, panel->backlight.min,
> + panel->backlight.max);
>
> - panel->backlight.enabled = (pch_ctl1 & BLM_PCH_PWM_ENABLE) &&
> - panel->backlight.level != 0;
> + panel->backlight.enabled = pch_ctl1 & BLM_PCH_PWM_ENABLE;
>
> return 0;
> }
> @@ -1459,11 +1460,13 @@ static int pch_setup_backlight(struct intel_connector *connector, enum pipe unus
> panel->backlight.min = get_backlight_min_vbt(connector);
>
> val = pch_get_backlight(connector);
> - panel->backlight.level = intel_panel_compute_brightness(connector, val);
> + val = intel_panel_compute_brightness(connector, val);
> + panel->backlight.level = clamp(val, panel->backlight.min,
> + panel->backlight.max);
>
> cpu_ctl2 = I915_READ(BLC_PWM_CPU_CTL2);
> panel->backlight.enabled = (cpu_ctl2 & BLM_PWM_ENABLE) &&
> - (pch_ctl1 & BLM_PCH_PWM_ENABLE) && panel->backlight.level != 0;
> + (pch_ctl1 & BLM_PCH_PWM_ENABLE);
>
> return 0;
> }
> @@ -1498,9 +1501,11 @@ static int i9xx_setup_backlight(struct intel_connector *connector, enum pipe unu
> panel->backlight.min = get_backlight_min_vbt(connector);
>
> val = i9xx_get_backlight(connector);
> - panel->backlight.level = intel_panel_compute_brightness(connector, val);
> + val = intel_panel_compute_brightness(connector, val);
> + panel->backlight.level = clamp(val, panel->backlight.min,
> + panel->backlight.max);
>
> - panel->backlight.enabled = panel->backlight.level != 0;
> + panel->backlight.enabled = val != 0;
>
> return 0;
> }
> @@ -1530,10 +1535,11 @@ static int i965_setup_backlight(struct intel_connector *connector, enum pipe unu
> panel->backlight.min = get_backlight_min_vbt(connector);
>
> val = i9xx_get_backlight(connector);
> - panel->backlight.level = intel_panel_compute_brightness(connector, val);
> + val = intel_panel_compute_brightness(connector, val);
> + panel->backlight.level = clamp(val, panel->backlight.min,
> + panel->backlight.max);
>
> - panel->backlight.enabled = (ctl2 & BLM_PWM_ENABLE) &&
> - panel->backlight.level != 0;
> + panel->backlight.enabled = ctl2 & BLM_PWM_ENABLE;
>
> return 0;
> }
> @@ -1562,10 +1568,11 @@ static int vlv_setup_backlight(struct intel_connector *connector, enum pipe pipe
> panel->backlight.min = get_backlight_min_vbt(connector);
>
> val = _vlv_get_backlight(dev_priv, pipe);
> - panel->backlight.level = intel_panel_compute_brightness(connector, val);
> + val = intel_panel_compute_brightness(connector, val);
> + panel->backlight.level = clamp(val, panel->backlight.min,
> + panel->backlight.max);
>
> - panel->backlight.enabled = (ctl2 & BLM_PWM_ENABLE) &&
> - panel->backlight.level != 0;
> + panel->backlight.enabled = ctl2 & BLM_PWM_ENABLE;
>
> return 0;
> }
> @@ -1607,10 +1614,11 @@ bxt_setup_backlight(struct intel_connector *connector, enum pipe unused)
> return -ENODEV;
>
> val = bxt_get_backlight(connector);
> - panel->backlight.level = intel_panel_compute_brightness(connector, val);
> + val = intel_panel_compute_brightness(connector, val);
> + panel->backlight.level = clamp(val, panel->backlight.min,
> + panel->backlight.max);
>
> - panel->backlight.enabled = (pwm_ctl & BXT_BLC_PWM_ENABLE) &&
> - panel->backlight.level != 0;
> + panel->backlight.enabled = pwm_ctl & BXT_BLC_PWM_ENABLE;
>
> return 0;
> }

--
Jani Nikula, Intel Open Source Technology Center