Re: [PATCH v5 2/2] memory: ti-emif-sram: introduce relocatable suspend/resume handlers

[Santosh Shilimkar]

On 11/10/2017 8:39 AM, Russell King - ARM Linux wrote:
> On Mon, Oct 16, 2017 at 08:31:59AM -0700, Santosh Shilimkar wrote:
> > Hi Russell,
> >
> > On 10/13/2017 1:59 PM, Dave Gerlach wrote:
> > > Certain SoCs like Texas Instruments AM335x and AM437x require parts
> > > of the EMIF PM code to run late in the suspend sequence from SRAM,
> > > such as saving and restoring the EMIF context and placing the memory
> > > into self-refresh.
> > >
> > > One requirement for these SoCs to suspend and enter its lowest power
> > > mode, called DeepSleep0, is that the PER power domain must be shut off.
> > > Because the EMIF (DDR Controller) resides within this power domain, it
> > > will lose context during a suspend operation, so we must save it so we
> > > can restore once we resume. However, we cannot execute this code from
> > > external memory, as it is not available at this point, so the code must
> > > be executed late in the suspend path from SRAM.
> > >
> > > This patch introduces a ti-emif-sram driver that includes several
> > > functions written in ARM ASM that are relocatable so the PM SRAM
> > > code can use them. It also allocates a region of writable SRAM to
> > > be used by the code running in the executable region of SRAM to save
> > > and restore the EMIF context. It can export a table containing the
> > > absolute addresses of the available PM functions so that other SRAM
> > > code can branch to them. This code is required for suspend/resume on
> > > AM335x and AM437x to work.
> > >
> > > In addition to this, to be able to share data structures between C and
> > > the ti-emif-sram-pm assembly code, we can automatically generate all of
> > > the C struct member offsets and sizes as macros by processing
> > > emif-asm-offsets.c into assembly code and then extracting the relevant
> > > data as is done for the generated platform asm-offsets.h files.
> > >
> > > Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx>
> > > ---
> > > v4->v5:
> > > * Simplify Makefile to generate include/generated/ti-emif-asm-offsets.h
> > If you are happy with this version from Dave, can I get your ack please?
> > I can add this to the driver-soc then.
>
> Does it need my ack anymore?  It doesn't touch anything in arch/arm.
> If you still want it, then... notwithstanding the loss of type checking
> that fncpy() gave and the new sram stuff messes up...
>
> Acked-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
Thanks Russell !!