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

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Nov 07, 2014 at 02:24:46PM +0200, Jani Nikula wrote:
> 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 form the VLV/CHV
> > backlight code.
> 
> The subject and this paragraph refer to VLV/CHV but this isn't really
> specific to those platforms.

Hmm. My assumption was that we can't get these with other platforms, but
the opregion might be a bit special I agree.

> 
> > If we still manage to get here with INVALID_PIPE we will now get a WARN
> > from the lower level functions and can then actually investigate further.
> >
> > vlv_get_backlight() still needs the check since that gets called in
> > response to userspace actual_brightness reads.
> 
> IIUC this bit won't be true if you add the backlight.enabled check as I
> suggested earlier.

Yeah, I think that should cover it.

> 
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_panel.c | 11 ++++-------
> >  1 file changed, 4 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> > index 2bc3309..0e2cb12 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);
> > @@ -662,10 +661,9 @@ void intel_panel_set_backlight_acpi(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;
> 
> I have a feeling we may get these requests from the BIOS whenever. In
> theory we should use the opregion ARDY field or somesuch to communicate
> whether we're ready or not (we always say we're ready like a scout) but
> even so we can't trust the BIOS to listen to what we say. Long story
> short we should probably leave this check in.

We do check backlight.enabled here as well, and I think we grab all the
required locks when servicing the opregion requests. So I'm thinking we
don't need the check here either. Or am I missing something?

> 
> With those fixed this LGTM.
> 
> BR,
> Jani.
> 
> 
> >  
> >  	mutex_lock(&dev_priv->backlight_lock);
> > @@ -740,9 +738,8 @@ 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 +946,7 @@ 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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> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center

-- 
Ville Syrjälä
Intel OTC
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