Re: [PATCH] arm: imx: mmdc_size: Increase row_max for imx8m

[Teresa Remmet <T.Remmet@phytec.de>]

Hello Ahmad,

Am Montag, dem 20.06.2022 um 14:02 +0200 schrieb Ahmad Fatoum:
> Hello,
> 
> On 20.05.22 16:23, Teresa Remmet wrote:
> > As DDRC_ADDRMAP7_ROW_B16 and DDRC_ADDRMAP7_ROW_B17 are used
> > now for the row size calculation we need to increase row_max to 18.
> > 
> > For LPDDR4 this only works in combination with ram timings
> > created with recent configuration spreadsheet versions.
> > With older versions the register DDRC_ADDRMAP7 may not be set and
> > calculation will lead to wrong results even with this patch.
> > 
> > Fixes: dad2b5636bd8 ("ARM: imx: Add imx8 support for 18 bit SDRAM
> > row size handle")
> > Signed-off-by: Teresa Remmet <t.remmet@phytec.de>
> 
> I have an out-of-tree i.MX8MM board with LPDDR4 that reported a
> correct size of 1G
> prior to this patch and now it reports 4G. DDRC_ADDRMAP7 is not
> explicitly initialized,
> but it's being read as zero, so the calculation seems to still be
> broken..

yes, this is why I added the note to the commit message. The RAM
timings of the board you are using have been created with a old version
of the spreadsheet ( < version 19 for i.MX8MM).
This issue is worked around when this patch is reverted as
DDRC_ADDRMAP7 is not taken into account. But calculating big ram sizes
will probably not work then.

I have set the DDRC_ADDRMAP7 register manually in the RAM configuration
in such a case. As I don't see a solution that fits for all. But would
be happy for one. :)

Regards,
Teresa

> 
> > ---
> >  arch/arm/mach-imx/esdctl.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm/mach-imx/esdctl.c b/arch/arm/mach-
> > imx/esdctl.c
> > index 8dd0ddbbc965..b070ebc62a45 100644
> > --- a/arch/arm/mach-imx/esdctl.c
> > +++ b/arch/arm/mach-imx/esdctl.c
> > @@ -488,7 +488,7 @@ static resource_size_t
> > imx8m_ddrc_sdram_size(void __iomem *ddrc)
> >  
> >  	return imx_ddrc_sdram_size(ddrc, addrmap,
> >  				   12, ARRAY_AND_SIZE(col_b),
> > -				   16, ARRAY_AND_SIZE(row_b),
> > +				   18, ARRAY_AND_SIZE(row_b),
> >  				   reduced_adress_space, true);
> >  }
> >  
> 
> 
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