linux-kernel - Re: [PATCH v7 2/2] ARM hibernation / suspend-to-disk

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Message-ID: <CADHgK6u7caDEZbt6Kj6VpzwADKytpk1068u_wQFFMvd3r1v1gw@mail.gmail.com>
Date:	Mon, 17 Mar 2014 15:07:51 -0700
From:	Sebastian Capella <sebastian.capella@...aro.org>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Stephen Boyd <sboyd@...eaurora.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Len Brown <len.brown@...el.com>,
	Jonathan Austin <jonathan.austin@....com>,
	Victor Kamensky <victor.kamensky@...aro.org>,
	Nicolas Pitre <nico@...aro.org>,
	Will Deacon <will.deacon@....com>,
	"Uwe Kleine-K??nig" <u.kleine-koenig@...gutronix.de>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Laura Abbott <lauraa@...eaurora.org>,
	Sricharan R <r.sricharan@...com>,
	Ben Dooks <ben.dooks@...ethink.co.uk>,
	Russ Dill <Russ.Dill@...com>,
	Catalin Marinas <catalin.marinas@....com>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Jiang Liu <liuj97@...il.com>
Subject: Re: [PATCH v7 2/2] ARM hibernation / suspend-to-disk

Thanks Russell!

On 16 March 2014 02:46, Russell King - ARM Linux <linux@....linux.org.uk> wrote:
> On Mon, Mar 10, 2014 at 11:32:17AM -0700, Sebastian Capella wrote:
...
> Let's look at the implementations...
>
> #define __pa(x)                 __virt_to_phys((unsigned long)(x))
> static inline phys_addr_t __virt_to_phys(unsigned long x)
> {
>         return (phys_addr_t)x - PAGE_OFFSET + PHYS_OFFSET;
> }
>
> So, __pa() returns a phys_addr_t (which may be either 32-bit or 64-bit).
>
> #define virt_to_pfn(kaddr)  (__pa(kaddr) >> PAGE_SHIFT)
>
> And that will do an appropriate shift to convert the phys_addr_t to a PFN,
> which will be fine to assign to an unsigned long variable.
>
> #define __phys_to_pfn(paddr)    ((unsigned long)((paddr) >> PAGE_SHIFT))
>
> This does the same thing, but has an explicit cast.
>
> So, the only difference between the two suggestions is that additional
> cast, which has no effect here.

Sounds good, thanks!

I was a little unsure about the page sizes that could affect all of
the implementations.

I'll make this change and repost, basically using virt_to_pfn in place
of the previous __pa_symbol, and remove unused declarations.

Thanks again!

Sebastian
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