Re: [PATCH 3/3] drm/i915/vlv: use min brightness from VBT

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Mar 31, 2014 at 11:13:57AM -0700, Jesse Barnes wrote:
> Going below the minimum value may affect the BLC_EN line, so try to use
> the VBT provided minimum where possible, otherwise use an experimentally
> derived value to prevent the panel from coming up.

"to prevent the panel form failing to come up" I hope?
-Daniel

> 
> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> ---
>  drivers/gpu/drm/i915/i915_drv.h    |  1 +
>  drivers/gpu/drm/i915/intel_bios.c  |  3 ++-
>  drivers/gpu/drm/i915/intel_drv.h   |  1 +
>  drivers/gpu/drm/i915/intel_panel.c | 10 +++++++++-
>  4 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index ff02225..3c40dcb 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1148,6 +1148,7 @@ struct intel_vbt_data {
>  	struct {
>  		u16 pwm_freq_hz;
>  		bool active_low_pwm;
> +		u8 min_brightness;
>  	} backlight;
>  
>  	/* MIPI DSI */
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index 4867f4c..e8dedf5 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -301,11 +301,12 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv, struct bdb_header *bdb)
>  
>  	dev_priv->vbt.backlight.pwm_freq_hz = entry->pwm_freq_hz;
>  	dev_priv->vbt.backlight.active_low_pwm = entry->active_low_pwm;
> +	dev_priv->vbt.backlight.min_brightness = entry->min_brightness;
>  	DRM_DEBUG_KMS("VBT backlight PWM modulation frequency %u Hz, "
>  		      "active %s, min brightness %u, level %u\n",
>  		      dev_priv->vbt.backlight.pwm_freq_hz,
>  		      dev_priv->vbt.backlight.active_low_pwm ? "low" : "high",
> -		      entry->min_brightness,
> +		      dev_priv->vbt.backlight.min_brightness,
>  		      backlight_data->level[panel_type]);
>  }
>  
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 0e91c40..053a968 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -166,6 +166,7 @@ struct intel_panel {
>  		bool present;
>  		u32 level;
>  		u32 max;
> +		u32 min;
>  		bool enabled;
>  		bool combination_mode;	/* gen 2/4 only */
>  		bool active_low_pwm;
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index 21c5e6f..27d7508 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -510,6 +510,9 @@ void intel_panel_set_backlight(struct intel_connector *connector, u32 level,
>  	else
>  		level = freq / max * level;
>  
> +	if (level < panel->backlight.min)
> +		level = panel->backlight.min;
> +
>  	panel->backlight.level = level;
>  	if (panel->backlight.device)
>  		panel->backlight.device->props.brightness = level;
> @@ -1047,7 +1050,12 @@ static int vlv_setup_backlight(struct intel_connector *connector)
>  
>  	ctl = I915_READ(VLV_BLC_PWM_CTL(PIPE_A));
>  	panel->backlight.max = ctl >> 16;
> -	if (!panel->backlight.max)
> +	panel->backlight.min = dev_priv->vbt.backlight.min_brightness;
> +	/* sane (i.e. checked on scope) default */
> +	if (!panel->backlight.min)
> +		panel->backlight.min = 64;
> +	if (!panel->backlight.max ||
> +	    panel->backlight.max < panel->backlight.min)
>  		return -ENODEV;
>  
>  	val = _vlv_get_backlight(dev, PIPE_A);
> -- 
> 1.8.4.2
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch