Re: [PATCH 2/7] backlight: apple_bl: use pr_debug/err instead ofprintk

From: Andrew Morton
Date: Tue May 15 2012 - 17:15:18 EST

On Tue, 15 May 2012 16:52:50 +0900
Jingoo Han <jg1.han@xxxxxxxxxxx> wrote:

> This patch uses pr_debug/err instead of printk to allow dynamic debugging.
> It also fixes checkpatch warnings as below:
> WARNING: Prefer pr_debug(... to printk(KERN_DEBUG, ...
> WARNING: Prefer pr_err(... to printk(KERN_ERR, ...
> ...
> --- a/drivers/video/backlight/apple_bl.c
> +++ b/drivers/video/backlight/apple_bl.c
> @@ -61,8 +61,7 @@ static int intel_chipset_send_intensity(struct backlight_device *bd)
> int intensity = bd->props.brightness;
> if (debug)
> - printk(KERN_DEBUG DRIVER "setting brightness to %d\n",
> - intensity);
> + pr_debug("setting brightness to %d\n", intensity);

This looks wrong. It replaces

apple_backlight: setting brightness to 42


setting brightness to 42

To do this properly we should do

#define pf_fmt "apple_backlight: "

before including printk.h. Conventionally this is done before
including any headers.

Also, apple_bl.c should explicitly include printk.h.

If doing this, please remove the DRIVER #define altogether.

Please check all the other drivers in this patchset. If they already
have custom things like DRIVER then remove that, define pr_fmt then
convert all the messages.

In other words, I'm recommending a functional change. For example,
drivers/video/backlight/generic_bl.c currently prints

Generic Backlight Driver Initialized

and I'm recommending that we switch this to

generic_bl: Generic Backlight Driver Initialized

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