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

From: Jiri Kosina
Date: Mon Feb 26 2007 - 16:26:28 EST


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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