[RFC PATCH] Consolidate SRAM support

[Nguyen Dinh-R00091]

Hi Russell,


>-----Original Message-----
>From: linux-arm-kernel-bounces at lists.infradead.org [mailto:linux-arm-kernel-
>bounces at lists.infradead.org] On Behalf Of Russell King - ARM Linux
>Sent: Friday, April 15, 2011 11:04 AM
>To: Rob Herring
>Cc: Kevin Hilman; davinci-linux-open-source at linux.davincidsp.com; Tony Lindgren; Sekhar Nori; linux-
>omap at vger.kernel.org; linux-arm-kernel at lists.infradead.org
>Subject: Re: [RFC PATCH] Consolidate SRAM support
>
>On Fri, Apr 15, 2011 at 08:39:55AM -0500, Rob Herring wrote:
>> Russell,
>>
>> On 04/15/2011 08:06 AM, Russell King - ARM Linux wrote:
>>> This is work in progress.
>>>
>>> We have two SoCs using SRAM, both with their own allocation systems,
>>> and both with their own ways of copying functions into the SRAM.
>>
>> It's more than that. Several i.MX chips use plat-mxc/iram_alloc.c.
>
>Hmm, that's nice - except for one issue.  According to my grep of
>arch/arm/ and drivers/, nothing uses iram_alloc().  So, does anything in
>the MX stuff use iram_alloc.c, or is it dead code left over from a
>previous experiment?

This function will be used for suspend code in the mx5x series. I just got done submitting a series of patches to Sascha for a simple suspend that does not need running code out of IRAM yet. The next set of suspend patches will be using these iram functions.

>
>The commit says:
>
>    ARM: imx: Add iram allocator functions
>
>    Add IRAM(Internal RAM) allocation functions using GENERIC_ALLOCATOR.
>    The allocation size is 4KB multiples to guarantee alignment. The
>    idea for these functions is for i.MX platforms to use them
>    to dynamically allocate IRAM usage.
>
>    Applies on 2.6.36-rc7
>
>> lpc32xx and pnx4008 also use iram, but do not have an allocator (only 1
>> user). Both are doing a copy the suspend code to IRAM and run it which
>> may also be a good thing to have generic code for. Several i.MX chips
>> also need to run from IRAM for suspend.
>
>We have support for copying functions to other bits of memory and getting
>the Thumb-ness right - see asm/fncpy.h.  So that's a separate patch to
>convert them over.
>
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