Re: [PATCH 1/1 v3] pwm_bl: Add support for backlight enable regulator

[Alex Courbot]

On 03/06/2013 11:41 AM, Andrew Chew wrote:
> > >    struct pwm_bl_data {
> > >    	struct pwm_device	*pwm;
> > >    	struct device		*dev;
> > > +	struct regulator	*en_supply;
> > > +	bool			en_supply_enabled;
> >
> > Couldn't you use regulator_is_enabled() and get rid of en_supply_enabled?
> > It would also ensure the driver performs correctly no matter what the initial
> > state of the regulator is.
>
> Are you sure this works?  I'm concerned about the (bizarre and unlikely) case
> where this supply is shared with another driver, so I use en_supply_enabled
> to track the state of the supply such that I can ignore that case.

You're right, consumers can share regulators and the calls to 
enable/disable need to be balanced. Also there is no way to check the 
intensity of the backlight prior to the change to detect a transition, 
so I guess your approach is indeed the most appropriate here.

Alex.

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