linux-kernel - RE: [PATCH] drivers/video/backlight/lp855x_bl.c: fix setting initial value for max

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Message-ID: <B567DBAB974C0544994013492B949F8E3813076468@EXMAIL03.scwf.nsc.com>
Date:	Mon, 20 Feb 2012 00:21:30 -0800
From:	"Kim, Milo" <Milo.Kim@...com>
To:	"Axel Lin" <axel.lin@...il.com>
cc:	"Richard Purdie" <rpurdie@...ys.net>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] drivers/video/backlight/lp855x_bl.c: fix setting
 initial value for max_brightness and brightness

Thanks for this patch.

But it would be better if max_brightness of platform data is removed.
Actually, there is no need to use max_brightness in the platform data.
All LP855x devices have 8-bit brightness control register.
Simply, value of max_brightness can be set to 255.

I'll send the patch for this.

Thanks & BR
Milo -

> -----Original Message-----
> From: Axel Lin [mailto:axel.lin@...il.com]
> Sent: Sunday, February 19, 2012 4:08 PM
> To: linux-kernel@...r.kernel.org
> Cc: Richard Purdie; Kim, Milo; Andrew Morton
> Subject: [PATCH] drivers/video/backlight/lp855x_bl.c: fix setting
> initial value for max_brightness and brightness
> 
> Current code does not always ensure
> pdata->initial_brightness <= pdata->max_brightness <= MAX_BRIGHTNESS.
> Fix it.
> 
> Signed-off-by: Axel Lin <axel.lin@...il.com>
> ---
>  drivers/video/backlight/lp855x_bl.c |   11 ++++++++---
>  1 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/video/backlight/lp855x_bl.c
> b/drivers/video/backlight/lp855x_bl.c
> index d32c097..29a3af2 100644
> --- a/drivers/video/backlight/lp855x_bl.c
> +++ b/drivers/video/backlight/lp855x_bl.c
> @@ -24,6 +24,7 @@
> 
>  #define BUF_SIZE		(20)
>  #define DEFAULT_BL_NAME		"lcd-backlight"
> +#define MAX_BRIGHTNESS		255
> 
>  struct lp855x {
>  	const char *chipid;
> @@ -171,10 +172,14 @@ static int lp855x_backlight_register(struct
> lp855x *lp)
>  	char *name = pdata->name ? : DEFAULT_BL_NAME;
> 
>  	props.type = BACKLIGHT_PLATFORM;
> +
> +	if (pdata->max_brightness > MAX_BRIGHTNESS)
> +		pdata->max_brightness = MAX_BRIGHTNESS;
> +	props.max_brightness = pdata->max_brightness;
> +
> +	if (pdata->initial_brightness > pdata->max_brightness)
> +		pdata->initial_brightness = pdata->max_brightness;
>  	props.brightness = pdata->initial_brightness;
> -	props.max_brightness =
> -		(pdata->max_brightness < pdata->initial_brightness) ?
> -		255 : pdata->max_brightness;
> 
>  	bl = backlight_device_register(name, lp->dev, lp,
>  				       &lp855x_bl_ops, &props);
> --
> 1.7.5.4
> 
>