linux-kernel - Re: [PATCH v5 3/3] backlight: lm3630a: add firmware node support

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Message-ID: <20190423140150.GA10071@basecamp>
Date:   Tue, 23 Apr 2019 10:01:50 -0400
From:   Brian Masney <masneyb@...tation.org>
To:     Dan Murphy <dmurphy@...com>
Cc:     lee.jones@...aro.org, daniel.thompson@...aro.org,
        jingoohan1@...il.com, robh+dt@...nel.org,
        jacek.anaszewski@...il.com, pavel@....cz, mark.rutland@....com,
        b.zolnierkie@...sung.com, dri-devel@...ts.freedesktop.org,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org,
        jonathan@...ek.ca
Subject: Re: [PATCH v5 3/3] backlight: lm3630a: add firmware node support

On Tue, Apr 23, 2019 at 08:49:20AM -0500, Dan Murphy wrote:
> > +static int lm3630a_parse_led_sources(struct fwnode_handle *node,
> > +				     int default_led_sources)
> > +{
> > +	u32 sources[LM3630A_NUM_SINKS];
> > +	int ret, num_sources, i;
> > +
> > +	num_sources = fwnode_property_read_u32_array(node, "led-sources", NULL,
> > +						     0);
> > +	if (num_sources < 0)
> > +		return default_led_sources;
> > +	else if (num_sources > ARRAY_SIZE(sources))
> > +		return -EINVAL;
> > +
> > +	ret = fwnode_property_read_u32_array(node, "led-sources", sources,
> > +					     num_sources);
> > +	if (ret)
> > +		return ret;
> > +
> > +	for (i = 0; i < num_sources; i++) {
> > +		if (sources[i] < LM3630A_SINK_0 || sources[i] > LM3630A_SINK_1)
> > +			return -EINVAL;
> > +
> > +		ret |= BIT(sources[i]);
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +static int lm3630a_parse_bank(struct lm3630a_platform_data *pdata,
> > +			      struct fwnode_handle *node, int *seen_led_sources)
> 
> Why is seen_led_sources passed in here?
> It is initialized on the stack in lm3630a_parse_node but the variable is never referenced in that API.

It's to see all of the led-sources that are configured across all of the
banks. If it is just in lm3630a_parse_bank(), then it won't catch the
following invalid configuration:

led@0 {
	reg = <0>;
	led-sources = <0 1>;
	label = "lcd-backlight";
	default-brightness = <200>;
};

led@1 {
	reg = <1>;
	default-brightness = <150>;
};

Brian