[U-Boot] [PATCH] armv8/fsl-layerscape: add IFC fixup for LS1043A with QSPI enabled

[Qianyu Gong <qianyu.gong@nxp.com>]

Hi Scott,

> -----Original Message-----
> From: Scott Wood [mailto:oss at buserror.net]
> Sent: Wednesday, March 30, 2016 4:45 AM
> To: Qianyu Gong <qianyu.gong@nxp.com>; u-boot at lists.denx.de; york sun
> <york.sun@nxp.com>
> Cc: Mingkai Hu <mingkai.hu@nxp.com>
> Subject: Re: [PATCH] armv8/fsl-layerscape: add IFC fixup for LS1043A with QSPI
> enabled
> 
> On Fri, 2016-03-11 at 10:18 +0000, Qianyu Gong wrote:
> > Hi Scott,
> >
> > > -----Original Message-----
> > > From: Scott Wood [mailto:oss at buserror.net]
> > > Sent: Tuesday, February 23, 2016 8:12 AM
> > > To: Qianyu Gong <qianyu.gong@nxp.com>; u-boot at lists.denx.de; york
> > > sun <york.sun@nxp.com>
> > > Cc: Mingkai Hu <mingkai.hu@nxp.com>
> > > Subject: Re: [PATCH] armv8/fsl-layerscape: add IFC fixup for LS1043A
> > > with QSPI enabled
> > >
> > > On Mon, 2016-02-22 at 18:05 +0800, Gong Qianyu wrote:
> > > > QSPI and IFC are pin-multiplexed on LS1043A. So if QSPI is
> > > > enabled, IFC should be disabled.
> > > > But just disable IFC driver in LS1043A Linux is not enough because
> > > > mdio-mux will access IFC address space -- actually it accesses
> > > > FPGA which is connected to IFC CS3. So disable the whole IFC node
> > > > in Linux device tree.
> > > >
> > > > Signed-off-by: Gong Qianyu <Qianyu.Gong@nxp.com>
> > > >
> > > > diff --git a/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
> > > > b/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
> > > > index 4e4861d..5bb3048 100644
> > > > --- a/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
> > > > +++ b/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
> > > > @@ -204,4 +204,11 @@ void ft_cpu_setup(void *blob, bd_t *bd)
> > > > #ifdef
> > > > CONFIG_FSL_LSCH3
> > > >  	fdt_fixup_smmu(blob);
> > > >  #endif
> > > > +
> > > > +#ifdef CONFIG_LS1043A
> > > > +#ifdef CONFIG_FSL_QSPI
> > > > +	do_fixup_by_compat(blob, "fsl,ifc",
> > > > +			   "status", "disabled", 8 + 1, 1); #endif
> > > > #endif
> > > >  }
> > >
> > > This muxing is done at runtime, right?  It isn't a case of the board
> > > hardwiring one or the other?  In that case, it should be handled at
> > > runtime here as well.
> > >   At a
> > > minimum, allow the user to use hwconfig to choose which they want to
> > > be accessible.  Ideally there would be something in the device tree
> > > to list the reason(s) for a device being disabled, so the OS knows
> > > it can regard the device as being enabled if it knows about and
> > > enables them all.
> > >
> > > -Scott
> >
> > Sorry for the late reply. We have been asking the silicon team for the
> > details of the pin muxing these days.
> > The conclusion is that all IFC interfaces(cs0/cs1/cs2) are disabled as
> > long as QSPI is enabled on LS1043AQDS board.
> > As I know, this muxing won't be handled in kernel. Since IFC is
> > disabled in U-Boot, IFC node would better be disabled in kernel as
> > well.
> > Also in such cases, users have no other choice.
> 
> Why should the user not have a choice to choose IFC over QSPI?  Where is the
> muxing configured?
> 
> -Scott

Because this muxing can't be changed at runtime.
Two ways so far to configure it:
1. SW6[1-4] switches on ls1043aqds board.
2. Modify QIXIS board config registers and reset the board.


Regards,
Qianyu