Re: [PATCH v4 01/14] ARM: mvebu: add Netgear RN102 support

["Sascha Hauer" <s.hauer@pengutronix.de>]

Hi Uwe,

On 2026-08-18 10:44, Uwe Kleine-König wrote:
> >
> > The only difference I can spot here between this function and the
> > existing variant in arch/arm/mach-mvebu/common.c is:
> > 
> > #define  DDR_SIZE_MASK                       0xff000000
> > 
> > whereas the common.c variant uses:
> > 
> > #define ARMADA_370_XP_DDR_SIZE_MASK     0xffff0000
> 
> Apart from the different value, the latter name is the better one B-)
> 
> > The latter goes down to this:
> > 
> > > commit 7351b6b5c59c7a280787998006f39a5cd3a2f18b
> > > Author: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > > Date:   Tue Jun 13 00:37:49 2017 +0200
> > >
> > >     ARM: mvebu: fix size mask for RAM window
> > >    
> > >     The size field in the window control register occupies bits 31:16. So
> > >     adapt ARMADA_370_XP_DDR_SIZE_MASK accordingly. This fixes detection of
> > >     RAM chips smaller than 32 MiB and so probably doesn't affect any
> > >     supported machine.
> > >    
> > >     Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > >     Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > >
> > > diff --git a/arch/arm/mach-mvebu/common.c b/arch/arm/mach-mvebu/common.c
> > > index 06bfb72615..fa971da11e 100644
> > > --- a/arch/arm/mach-mvebu/common.c
> > > +++ b/arch/arm/mach-mvebu/common.c
> > > @@ -47,7 +47,7 @@
> > >  #define ARMADA_370_XP_SDRAM_BASE       (IOMEM(MVEBU_REMAP_INT_REG_BASE) + 0x20000)
> > >  #define ARMADA_370_XP_DDR_SIZE_CSn(n)  (0x184 + ((n) * 0x8))
> > >  #define ARMADA_370_XP_DDR_SIZE_ENABLED BIT(0)
> > > -#define ARMADA_370_XP_DDR_SIZE_MASK    0xff000000
> > > +#define ARMADA_370_XP_DDR_SIZE_MASK    0xffff0000
> > > 
> > >  /*
> > >   * Marvell MVEBU SoC id and revision can be read from any PCIe
> > 
> > @Uwe, Where did you get that information from. Could it be that we
> > should just revert this one given that it seems to be untested on your
> > side?
> 
> 0xffff0000 is in line with
> https://datasheet.datasheetarchive.com/originals/crawler/marvell.com/002fa441a27967d992f905776d519926.pdf
> (page 630). So I'd expect that 0xffff0000 is correct, but I don't care
> much.

Page 630 describes the register at offset 0x20000. I think the correct
page to look at is 626 which describes 0x20184 aka ARMADA_370_XP_DDR_SIZE_CSn(0).

That one has the window size in the upper 8 bit. Looks like we should
just revert 7351b6b5c59c. @Luca, does the SDRAM size detection work for
you with that patch reverted?

Sascha

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