[PATCH] powerpc/85xx: DTS - re-organize the SPI partitions property

[Hu Mingkai-B21284]

Scott,
Sorry for the delayed response.
Please fine my comments.
Thanks,
Mingkai

> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Thursday, September 12, 2013 9:16 AM
> To: Hu Mingkai-B21284
> Cc: Wood Scott-B07421; linuxppc-dev at ozlabs.org
> Subject: Re: [PATCH] powerpc/85xx: DTS - re-organize the SPI partitions
> property
> 
> On Tue, 2013-09-10 at 21:07 -0500, Hu Mingkai-B21284 wrote:
> >
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Wednesday, September 11, 2013 7:33 AM
> > > To: Hu Mingkai-B21284
> > > Cc: linuxppc-dev at ozlabs.org
> > > Subject: Re: [PATCH] powerpc/85xx: DTS - re-organize the SPI
> > > partitions property
> > >
> > > What happens to exsting users whose flash is laid out the existing
> > > way, when they upgrade to these device trees?
> > >
> >
> > The SPI flash layout should be mapping the new device tree.
> >
> > If the existing device tree is used to deploy the SPI flash, the
> > following issues must be run into as the commit message described:
> >
> > 1. Kernel images would be overlapped with U-Boot image.
> > 2. Kernel images would be overlapped with FMAN ucode.
> > 3. Saving environment variables will crash the kernel image.
> 
> Has the SPI U-Boot image always been larger than 512K for all these
> platforms?  Why, given that we're under 512K for other boot modes?
> 

For DPAA platform, the ld script used to link the u-boot image is 
"./arch/powerpc/cpu/mpc85xx/u-boot.lds" which will generate the 512K u-boot
Image. This image will be split into 64bytes and appended PBL command for 
Each 64bytes pieces, so the size of final image must be greater than 512K.

The same applies to the non-DPAA platform which doesn't support TPL.

For non-DPAA platform which support TPL, the image size is also greater than 512K.

> > > We really should not be putting partition layout info in the device
> > > tree to begin with...
> > >
> > OK, I will remove the layout diagram in the commit message.
> 
> That's not what I meant.  I meant that the dts should be describing
> hardware, and this is the sort of trouble we run into when we deviate
> from that.  A better way would be to use the mtdparts command line option.
> Even better would be some sort of on-flash partition table.
> 

You're right, but maybe some customer has already used the device tree partition table...

Thanks,
Mingkai