linux-kernel - Re: [RFC 06/18] regmap: Formalise use of non-bus context

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Message-ID: <1389892813.3496.82.camel@hornet>
Date:	Thu, 16 Jan 2014 17:20:13 +0000
From:	Pawel Moll <pawel.moll@....com>
To:	Grant Likely <grant.likely@...retlab.ca>
Cc:	Mark Brown <broonie@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Arnd Bergmann <arnd@...db.de>, Jon Medhurst <tixy@...aro.org>,
	"arm@...nel.org" <arm@...nel.org>, Olof Johansson <olof@...om.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [RFC 06/18] regmap: Formalise use of non-bus context

On Thu, 2014-01-16 at 17:09 +0000, Grant Likely wrote:
> > First of all, it's just a generalization of the free_context already
> > existing in regmap_bus (and used by regmap-mmio). And in case of this
> > series it is being used to release extra resource added allocated for a
> > "busless" regmap_config. Briefly, I'm using devm_regmap_init() to
> > "attach" a custom regmap configuration to a device when it is being
> > created (which is then dev_get_regmap()-ed in the driver, as you saw in
> > the regulator patch) and its context is a pointer to kzallocated data.
> > free_context is used to release it when devm resource is being removed.
> 
> Have you thought through all the implications here? What you've
> described effectively changes the devm model. devm operates under the
> assumption that devm data only exists between probe() and remove() time.
> If you 'preload' devm data then the preloaded data will get discarded at
> remove() time which breaks if the driver is remove and probed again at
> runtime.

Uh. Right, you're correct, I've missed that (obvious) fact :-(

I will get the drivers back to "vexpress_regmap_init()" model or try to
find a way of "attaching" a regmap pointer(s?) to a struct device. If it
makes sense at all...

Paweł

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