Re: [PATCH v2 6/6] drm/i915: Remove most INVALID_PIPE checks from the backlight code

[Jani Nikula <jani.nikula@intel.com>]

On Fri, 07 Nov 2014, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Now that the backlight device no longer gets registered too early we
> should be able to drop most of the INVALID_PIPE checks from the backlight
> code.
>
> The only exceptio is the opregion stuff where we may (in theory at
> least) get a request from the BIOS already during driver init as soon as
> the backlight setup has been done. In which case we can still get the
> INVALID_PIPE from intel_get_pipe_from_connector(). So leave that check
> in place, and add a comment explaining why.
>
> For the rest, if we still manage to get here with INVALID_PIPE on
> VLV/CHV we will now get a WARN from the lower level functions and
> can then actually investigate further.
>
> v2: Leave the check in the BIOS related code (Jani)
>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_panel.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index 708642a..c45b127 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -634,10 +634,9 @@ static void intel_panel_set_backlight(struct intel_connector *connector,
>  	struct drm_device *dev = connector->base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_panel *panel = &connector->panel;
> -	enum pipe pipe = intel_get_pipe_from_connector(connector);
>  	u32 hw_level;
>  
> -	if (!panel->backlight.present || pipe == INVALID_PIPE)
> +	if (!panel->backlight.present)
>  		return;
>  
>  	mutex_lock(&dev_priv->backlight_lock);
> @@ -665,6 +664,12 @@ void intel_panel_set_backlight_acpi(struct intel_connector *connector,
>  	enum pipe pipe = intel_get_pipe_from_connector(connector);
>  	u32 hw_level;
>  
> +	/*
> +	 * INVALID_PIPE may occur during driver init because
> +	 * connection_mutex isn't held across the entire backlight
> +	 * setup + modeset readout, and the BIOS can issue the
> +	 * requests at any time.
> +	 */
>  	if (!panel->backlight.present || pipe == INVALID_PIPE)
>  		return;
>  
> @@ -740,9 +745,8 @@ void intel_panel_disable_backlight(struct intel_connector *connector)
>  	struct drm_device *dev = connector->base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_panel *panel = &connector->panel;
> -	enum pipe pipe = intel_get_pipe_from_connector(connector);
>  
> -	if (!panel->backlight.present || pipe == INVALID_PIPE)
> +	if (!panel->backlight.present)
>  		return;
>  
>  	/*
> @@ -949,7 +953,7 @@ void intel_panel_enable_backlight(struct intel_connector *connector)
>  	struct intel_panel *panel = &connector->panel;
>  	enum pipe pipe = intel_get_pipe_from_connector(connector);
>  
> -	if (!panel->backlight.present || pipe == INVALID_PIPE)
> +	if (!panel->backlight.present)
>  		return;
>  
>  	DRM_DEBUG_KMS("pipe %c\n", pipe_name(pipe));
> -- 
> 2.0.4
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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