linux-kernel - Re: [PATCH V4 5/8] backlight: qcom-wled: Restructure the driver for WLED3

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Date:   Mon, 6 Aug 2018 22:37:05 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Kiran Gunda <kgunda@...eaurora.org>
Cc:     jingoohan1@...il.com, lee.jones@...aro.org,
        b.zolnierkie@...sung.com, dri-devel@...ts.freedesktop.org,
        daniel.thompson@...aro.org, jacek.anaszewski@...il.com,
        pavel@....cz, robh+dt@...nel.org, mark.rutland@....com,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH V4 5/8] backlight: qcom-wled: Restructure the driver for
 WLED3

On Mon 09 Jul 03:22 PDT 2018, Kiran Gunda wrote:
> diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
[..]
> @@ -365,6 +434,15 @@ static int wled_configure(struct wled *wled, struct device *dev)
>  
>  	cfg->num_strings = cfg->num_strings + 1;
>  
> +	string_len = of_property_count_elems_of_size(dev->of_node,
> +						     "qcom,enabled-strings",
> +						     sizeof(u32));
> +	if (string_len > 0)
> +		rc = of_property_read_u32_array(dev->of_node,
> +						"qcom,enabled-strings",
> +						wled->cfg.enabled_strings,

qcom,enabled-strings is listed as optional, but without it we will end
up with qcom,num-strings zeros in an array.  Initialize
wled->cfg.enabled_strings to 0,1,2,3 and the driver will be backwards
compatible.

I also think that if you do qcom,enabled-strings = <0, 1, 2>; there's no
need to also specify qcom,num-strings = <3>; and we can just use
string_len for num_strings.

> +						sizeof(u32));
> +
>  	return 0;
>  }

Regards,
Bjorn