linux-kernel - Re: [PATCH 4/7] regulator: anatop-regulator: convert to use imx-syscon to access anatop register

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Date:	Fri, 24 Aug 2012 10:37:50 +0800
From:	Dong Aisheng <b29396@...escale.com>
To:	Stephen Warren <swarren@...dotorg.org>
CC:	Zhao Richard-B20223 <B20223@...escale.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linus.walleij@...ricsson.com" <linus.walleij@...ricsson.com>,
	"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
	"shawn.guo@...aro.org" <shawn.guo@...aro.org>,
	"kernel@...gutronix.de" <kernel@...gutronix.de>,
	"grant.likely@...retlab.ca" <grant.likely@...retlab.ca>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	"sameo@...ux.intel.com" <sameo@...ux.intel.com>,
	"lrg@...com" <lrg@...com>,
	"broonie@...nsource.wolfsonmicro.com" 
	<broonie@...nsource.wolfsonmicro.com>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>
Subject: Re: [PATCH 4/7] regulator: anatop-regulator: convert to use
 imx-syscon to access anatop register

On Fri, Aug 24, 2012 at 01:56:58AM +0800, Stephen Warren wrote:
> On 08/23/2012 12:12 AM, Richard Zhao wrote:
> > On Wed, Aug 22, 2012 at 11:21:03PM -0600, Stephen Warren wrote:
> >> On 08/22/2012 01:18 AM, Dong Aisheng wrote:
> >>> Signed-off-by: Dong Aisheng <dong.aisheng@...aro.org>
> >>
> >>> diff --git a/drivers/regulator/anatop-regulator.c b/drivers/regulator/anatop-regulator.c
> >>
> >>> @@ -109,7 +110,11 @@ static int __devinit anatop_regulator_probe(struct platform_device *pdev)
> >>>  	rdesc->ops = &anatop_rops;
> >>>  	rdesc->type = REGULATOR_VOLTAGE;
> >>>  	rdesc->owner = THIS_MODULE;
> >>> -	sreg->mfd = anatopmfd;
> >>> +
> >>> +	sreg->anatop = of_parse_phandle(np, "fsl,anatop", 0);
> >>> +	if (!sreg->anatop)
> >>> +		return -ENODEV;
> >>
> >> In fact, that imx_syscon_lookup function I proposed could even do the
> >> of_parse_phandle() internally, so perhaps:
> >>
> >> foo->syscon_dev = imx_syscon_lookup(np, "fsl,anatop", 0);
> >> if (IS_ERR(foo->syscon_dev))
> >>     return PTR_ERR(foo->syscon_dev);
> >>
> >> with imx_syscon_lookup() internally knowing when to return EPROBE_DEFER
> >> rather than any other permanent error code (e.g. for missing property,
> >> bad phandle, etc.)
> >
> > In some case that we access register in machine code, we don't have any
> > phandle. The node is got by find compatible or by path.
> 
> That sounds a little odd; why not just use a phandle consistently
> everywhere?
Maybe for some places we do not have that device node, e.g:
arch/arm/mach-imx/mach-imx6q.c

> 
> Either way though, I could imagine still putting all the lookup code
> into the syscon driver; just have different functions for the different
> lookup methods:
> 
> imx_syscon_lookup_by_phandle(np, char *property_name)
Probably we do not need the left two lookup, below seems also ok if needed:
np = of_find_compatible_node(NULL, NULL, "fsl,imx6q-anatop");
regmap = imx_syscon_lookup_by_phandle(np, property_name)
Then we do not need to handle how to find the compatible node.

> imx_syscon_lookup_by_compatible(char *compatible
> imx_syscon_lookup_by_path(char *node_path)

Regards
Dong Aisheng

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