RE: [Patch V1 2/2] spi: fsl-lpspi: add VLLS mode support

[Pandy Gao <pandy.gao-3arQi8VN3Tc@public.gmane.org>]

From: Mark Brown <mailto:broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Sent: Wednesday, January 18, 2017 3:04 AM
> To: Pandy Gao <pandy.gao-3arQi8VN3Tc@public.gmane.org>
> Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Subject: Re: [Patch V1 2/2] spi: fsl-lpspi: add VLLS mode support
> 
> On Tue, Jan 17, 2017 at 07:03:28AM +0000, Pandy Gao wrote:
> 
> > > > The patch recovers the pinctrl setting when exit VLLS mode.
> 
> > > Why is this a change here and not in the pinctrl driver?  It sounds
> > > like it's the pinctrl driver that's forgetting the settings and
> > > should be restoring them on resume but perhaps I'm missing
> something here.
> 
> > If the pinctrl driver restores the setting on resume, then all device
> > node should be scanned,  which is irregular.
> 
> What would restoring the configuration have to do with scanning the
> device tree?  The changelog says this is just reapplying the same
> settings we started out with so it's just a case of restoring the state of
> the device after a runtime resume which is a perfectly normal thing for
> a driver to do.

We can reapply  the initial settings as the configurations defined in
device node iomuxc in pinctrl driver.  However, I think there are some
limitations.  For example, conflicts may exist between enet1grp and
ecspi3grp, which is not easy for the pinctrl  driver to find out.

&iomuxc {
	pinctrl_ecspi3: ecspi3grp 
	{
		...
	};

            	pinctrl_enet1: enet1grp
	 {
		...
	};
}

Best Regards
Gao Pan
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