Re: [patch] collie: enable frontlight

[Pavel Machek]

Hi!

> > +static spinlock_t fl_lock = SPIN_LOCK_UNLOCKED;
> > +
> > +#define LCM_ALC_EN	0x8000
> > +
> > +void frontlight_set(struct locomo *lchip, int duty, int vr, int bpwf)
> > +{
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&fl_lock, flags);
> > +	locomo_writel(bpwf, lchip->base + LOCOMO_FRONTLIGHT + LOCOMO_ALS);
> > +	udelay(100);
> > +	locomo_writel(duty, lchip->base + LOCOMO_FRONTLIGHT + LOCOMO_ALD);
> > +	locomo_writel(bpwf | LCM_ALC_EN, lchip->base + LOCOMO_FRONTLIGHT + LOCOMO_ALS);
> > +	spin_unlock_irqrestore(&fl_lock, flags);
> > +}
> 
> ick, a 100 microsecond glitch, quite unnecessary.  Why not use a semaphore
> here, if any locking is actually needed?  (It's called from device probe -
> there's higher-level serialisation, no?)

Suspend (locomo_suspend) touches frontlight registers, too, and it
does it under spinlock => converting to semaphore would not too
simple. As it is only one glitch during probe, it should not hurt that
much...
								Pavel
-- 
Thanks, Sharp!
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