On Mon, 2007-02-26 at 22:25 +0100, Jiri Kosina wrote:
> 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?
In the above context, && is correct, || isn't.
We want to blank (set to 0) if either fb_blank or power isn't set to
FB_BLANK_UNBLANK. This is the same as setting to brightness if both
fb_blank and power are set to FB_BLANK_UNBLANK. This is what the above
expression does.
Richard
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