[U-Boot] [PATCH] ppc4xx: Don't fixup NOR flash node size on Ebony

[Wolfgang Denk]

Dear Stefan Roese,

In message <201009151543.02284.sr at denx.de> you wrote:
> 
> > The "reg" property of NOR FLASH device tree nodes *should* be updated
> > with the correct size of the NOR flash as determined by the CFI
> > driver; on this board, this should be 512 KiB.
> 
> This value of 512KiB is already present in the NOR flash device tree node.

It should be updated in any case using the values as determined by the
CFI flash driver.

> > Both the bd_info command and the device tree should report a NOR flash
> > size of 512 KiB.
> 
> bdinfo shows 4.5MiB of flashsize, since Ebony has additional flash devices at 

OK.

> different chip-selects. There are additional device tree nodes to describe 
> these NOR flash devices as well. The total of all NOR flash device tree nodes 
> will be 4.5MiB as well, using this patch. With out this patch it is 5MiB.

Then there is a bug somewhere, because you seem to add 4 + 1 MiB
flash sizes when the real sizes are only 4 MiB + 512 KiB.

> > The SRAM size is completely independent of that. As we don't provide
> > auto-sizing for the sram, the board config file should contain (read:
> > needs to get fixed to contain) the correct CONFIG_SYS_SRAM_BASE and
> > CONFIG_SYS_SRAM_SIZE settings (with CONFIG_SYS_SRAM_SIZE = 512 KiB).
> > 
> > Both the bd_info command and the device tree should report a SRAM size
> > of 512 KiB.
> 
> My patch doesn't touch any SRAM lated stuff. It fixes a real issue, where 
> Ebony currently crashes upon Linux booting trying to map/detect NOR flash 
> devices at an inaccessible memory region.

I wanted to point out that the SRAM settings are missing and need
fixing, too.

> This patch disables the PPC4xx specific device-tree-blob fixup code, which is 
> enabled per default for all AMCC/APM eval boards, that writes the chip-select 
> size into the size of the "reg" property of the NOR flash device tree nodes. 

Ah!  That's the bug, then. You must not write any map size, but only
the real flash device size as determined by the CFI driver.

> This fixup code is intended for boards with multiple flash configurations, 
> passing the detected flash size in the device tree node to the Linux kernel. 
> On Ebony this code doesn't work correctly, since it has an 512KiB SRAM and an 
> 512KiB NOR flash connected to one chip-select. This code updates incorrectly 
> 1MiB of chip-select size into the NOR flash device tree node.

It does not work correctly because you are incorrectly using the size
of the chip select mapping when you should be using the flash device
size instead.  Please fix this problem.

Best regards,

Wolfgang Denk

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