linux-kernel - Re: [PATCH] ACPI: ibm-acpi: improve backlight power handling (v2)

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Message-ID: <Pine.LNX.4.64.0702262217490.10496@twin.jikos.cz>
Date:	Mon, 26 Feb 2007 22:25:55 +0100 (CET)
From:	Jiri Kosina <jikos@...os.cz>
To:	Henrique de Moraes Holschuh <hmh@....eng.br>
cc:	Richard Purdie <rpurdie@...ys.net>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI: ibm-acpi: improve backlight power handling (v2)

On Mon, 26 Feb 2007, Henrique de Moraes Holschuh wrote:

>  static int brightness_update_status(struct backlight_device *bd)
>  {
> -	return brightness_set(bd->props.brightness);
> +	return brightness_set(
> +		(bd->props.fb_blank == FB_BLANK_UNBLANK &&
> +		 bd->props.power == FB_BLANK_UNBLANK) ?
> +				bd->props.brightness : 0);
>  }

Are you sure about the '&&'? The original patch I submitted to you earlier 
today was checking for (bd->props.fb_blank == FB_BLANK_UNBLANK || 
bd->props.power == FB_BLANK_UNBLANK), and I tested it (to some extent) and 
it worked well - no sudden unblanking without reason, no blinking, etc.

I also think that common sense implies that the condition should be 
logical or - backlight layer could request blanking without requesting 
powering the device off, right? We want to handle unblanking from such 
situation properly, which doesn't necessairly mean we will get 
bd->props.power == FB_BLANK_UNBLANK, right?

-- 
Jiri Kosina
-
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