Re: [PATCH v1] pinctrl: intel: Allow to request locked pins

[Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>]

On Tue, Aug 06, 2019 at 02:45:17PM +0300, Andy Shevchenko wrote:
> On Tue, Aug 06, 2019 at 02:01:26PM +0300, Mika Westerberg wrote:
> > On Fri, Jul 26, 2019 at 11:08:30PM +0300, Andy Shevchenko wrote:
> > > Some firmwares would like to protect pins from being modified by OS
> > > and at the same time provide them to OS as a resource. So, the driver
> > > in such circumstances may request pin and may not change its state.
> > 
> > This is definitely good idea.
> 
> Thanks for review, my answers below.
> 
> > >  	 * the pad is considered unlocked. Any other case means that it is
> > >  	 * either fully or partially locked and we don't touch it.
> > 
> > I think you should update the above comment as well.
> 
> Will do for v2.
> 
> > >  	raw_spin_lock_irqsave(&pctrl->lock, flags);
> > >  
> > > -	if (!intel_pad_usable(pctrl, pin)) {
> > > +	if (!intel_pad_owned_by_host(pctrl, pin)) {
> > >  		raw_spin_unlock_irqrestore(&pctrl->lock, flags);
> > >  		return -EBUSY;
> > >  	}
> > >  
> > > +	if (!intel_pad_is_unlocked(pctrl, pin)) {
> > > +		raw_spin_unlock_irqrestore(&pctrl->lock, flags);
> > > +		return 0;
> > 
> > Hmm, if I'm reading this right it still does not allow requesting locked
> > pins. What I'm missing here?
> 
> We do not return an error code here, so pin is left requested but pad
> configuration register untouched.

Indeed, now it is clear. Thanks for explaining :)