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

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Message-ID: <f8499848-1490-cee5-c943-fa7fb77236ce@ti.com>
Date:   Tue, 23 Apr 2019 14:02:51 -0500
From:   Dan Murphy <dmurphy@...com>
To:     Brian Masney <masneyb@...tation.org>
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

Brian

On 4/23/19 11:00 AM, Brian Masney wrote:
> On Tue, Apr 23, 2019 at 10:31:41AM -0500, Dan Murphy wrote:
>> On 4/23/19 9:01 AM, Brian Masney wrote:
>>> 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:
>>>
>>
>> Ok I see what it is for now.
>>
>> Not sure why it is declared as a pointer though.
> 
> It's so that lm3630a_parse_bank() can update that value with the
> led-sources that have been seen. Otherwise, the changes wouldn't make
> their way back out to the outer function.
> 

OK.  Thats another way to do it.  I may have just done a return with the value.

Otherwise

Reviewed-by: Dan Murphy <dmurphy@...com>

> Brian
>