linux-kernel - Re: [RFC][PATCH 2/2] ARM: ioremap: Add IO mapping space reused support.

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Date:	Wed, 14 May 2014 10:13:22 +0800
From:	Richard Lee <superlibj8301@...il.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	linux-arm-kernel@...ts.infradead.org, linux@....linux.org.uk,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Richard Lee <superlibj@...il.com>
Subject: Re: [RFC][PATCH 2/2] ARM: ioremap: Add IO mapping space reused support.

On Tue, May 13, 2014 at 4:43 PM, Arnd Bergmann <arnd@...db.de> wrote:
> On Tuesday 13 May 2014 09:45:08 Richard Lee wrote:
>> > On Mon, May 12, 2014 at 3:51 PM, Arnd Bergmann <arnd@...db.de> wrote:
>> > On Monday 12 May 2014 10:19:55 Richard Lee wrote:
>> >> For the IO mapping, for the same physical address space maybe
>> >> mapped more than one time, for example, in some SoCs:
>> >> 0x20000000 ~ 0x20001000: are global control IO physical map,
>> >> and this range space will be used by many drivers.
>> >> And then if each driver will do the same ioremap operation, we
>> >> will waste to much malloc virtual spaces.
>> >>
>> >> This patch add IO mapping space reused support.
>> >>
>> >> Signed-off-by: Richard Lee <superlibj@...il.com>
>> >
>> > What happens if the first driver then unmaps the area?
>> >
>>
>> If the first driver will unmap the area, it shouldn't do any thing
>> except decreasing the 'used' counter.
>
> Ah, for some reason I didn't see your first patch that introduces
> that counter.
>

It's "[PATCH 1/2] mm/vmalloc: Add IO mapping space reused".

Thanks,

BRs
Richard



>         Arnd
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