linux-kernel - Re: [PATCH v3 17/21] ARM: at91: merge SRAM Memory banks thanks to mirroring

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Date:	Fri, 24 Feb 2012 17:54:43 +0100
From:	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
To:	Ryan Mallon <rmallon@...il.com>
Cc:	Nicolas Ferre <nicolas.ferre@...el.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux@....linux.org.uk, arnd@...db.de
Subject: Re: [PATCH v3 17/21] ARM: at91: merge SRAM Memory banks thanks to
 mirroring

On 08:47 Fri 24 Feb     , Ryan Mallon wrote:
> On 24/02/12 01:26, Nicolas Ferre wrote:
> 
> > From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
> > 
> > On at91sam9260 and at91sam9g20 the SRAM banks are mirrored. We can
> > merge them together to be able to have bigger and continuous
> > internal RAM.
> 
> I think this patch needs some comments in the code. As mentioned in the
> last round, this functionality is not documented, so it is not obvious
> how/why this works. This is especially true for any user who has
> problems with this code and then tries to look up those addresses in
> their at91 manual only to find the regions are reserved.
> 
> Nicolas, are you able to give an official Atmel stance on this?
you have the ack from Nico and he send the e-mail

Best Regards,
J.
> 
> ~Ryan
> 
> > Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
> > Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
> > ---
> >  arch/arm/mach-at91/at91sam9260.c              |   13 +++++--------
> >  arch/arm/mach-at91/include/mach/at91sam9260.h |    4 ++++
> >  2 files changed, 9 insertions(+), 8 deletions(-)
> > 
> > diff --git a/arch/arm/mach-at91/at91sam9260.c b/arch/arm/mach-at91/at91sam9260.c
> > index 14882ae..4ade265 100644
> > --- a/arch/arm/mach-at91/at91sam9260.c
> > +++ b/arch/arm/mach-at91/at91sam9260.c
> > @@ -310,15 +310,12 @@ static void __init at91sam9xe_map_io(void)
> >  
> >  static void __init at91sam9260_map_io(void)
> >  {
> > -	if (cpu_is_at91sam9xe()) {
> > +	if (cpu_is_at91sam9xe())
> >  		at91sam9xe_map_io();
> > -	} else if (cpu_is_at91sam9g20()) {
> > -		at91_init_sram(0, AT91SAM9G20_SRAM0_BASE, AT91SAM9G20_SRAM0_SIZE);
> > -		at91_init_sram(1, AT91SAM9G20_SRAM1_BASE, AT91SAM9G20_SRAM1_SIZE);
> > -	} else {
> > -		at91_init_sram(0, AT91SAM9260_SRAM0_BASE, AT91SAM9260_SRAM0_SIZE);
> > -		at91_init_sram(1, AT91SAM9260_SRAM1_BASE, AT91SAM9260_SRAM1_SIZE);
> > -	}
> > +	else if (cpu_is_at91sam9g20())
> > +		at91_init_sram(0, AT91SAM9G20_SRAM_BASE, AT91SAM9G20_SRAM_SIZE);
> > +	else
> > +		at91_init_sram(0, AT91SAM9260_SRAM_BASE, AT91SAM9260_SRAM_SIZE);
> >  }
> >  
> >  static void __init at91sam9260_ioremap_registers(void)
> > diff --git a/arch/arm/mach-at91/include/mach/at91sam9260.h b/arch/arm/mach-at91/include/mach/at91sam9260.h
> > index 2e47b6d..08ae9af 100644
> > --- a/arch/arm/mach-at91/include/mach/at91sam9260.h
> > +++ b/arch/arm/mach-at91/include/mach/at91sam9260.h
> > @@ -113,6 +113,8 @@
> >  #define AT91SAM9260_SRAM0_SIZE	SZ_4K		/* Internal SRAM 0 size (4Kb) */
> >  #define AT91SAM9260_SRAM1_BASE	0x00300000	/* Internal SRAM 1 base address */
> >  #define AT91SAM9260_SRAM1_SIZE	SZ_4K		/* Internal SRAM 1 size (4Kb) */
> > +#define AT91SAM9260_SRAM_BASE	0x002FF000	/* Internal SRAM base address */
> > +#define AT91SAM9260_SRAM_SIZE	SZ_8K		/* Internal SRAM size (8Kb) */
> >  
> >  #define AT91SAM9260_UHP_BASE	0x00500000	/* USB Host controller */
> >  
> > @@ -126,6 +128,8 @@
> >  #define AT91SAM9G20_SRAM0_SIZE	SZ_16K		/* Internal SRAM 0 size (16Kb) */
> >  #define AT91SAM9G20_SRAM1_BASE	0x00300000	/* Internal SRAM 1 base address */
> >  #define AT91SAM9G20_SRAM1_SIZE	SZ_16K		/* Internal SRAM 1 size (16Kb) */
> > +#define AT91SAM9G20_SRAM_BASE	0x002FC000	/* Internal SRAM base address */
> > +#define AT91SAM9G20_SRAM_SIZE	SZ_32K		/* Internal SRAM size (32Kb) */
> >  
> >  #define AT91SAM9G20_UHP_BASE	0x00500000	/* USB Host controller */
> >  
> 
> 
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