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

[Qianyu Gong]

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 at nxp.com>; u-boot at lists.denx.de; york sun
> <york.sun at nxp.com>
> Cc: Mingkai Hu <mingkai.hu at 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 at 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.


Regards,
Qianyu