Re: [RESEND PATCH] arm: Enlarge IO_SPACE_LIMIT needed for some SoC

From: Russell King - ARM Linux admin
Date: Sat May 08 2021 - 14:51:03 EST

On Sat, May 08, 2021 at 07:55:35PM +0200, Ansuel Smith wrote:
> Ipq8064 SoC requires larger IO_SPACE_LIMIT or second and third pci port
> fails to register the IO addresses and connected device doesn't work.
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.9+
> Signed-off-by: Ansuel Smith <ansuelsmth@xxxxxxxxx>

I don't see any consideration of whether this increase results in any
clashes with any other related areas. Also, there is no update of the
memory layout documentation.

The memory layout documentation says:

=============== =============== ===============================================
Start End Use
=============== =============== ===============================================
fee00000 feffffff Mapping of PCI I/O space. This is a static
mapping within the vmalloc space.

which means there's a maximum of 0x001fffff available. You are
increasing it's size from 0x000fffff to 0x00ffffff. This means it
expands from 0xfee00000 through to 0xffdfffff.

This conflicts with these entries:

ffc80000 ffefffff Fixmap mapping region. Addresses provided
by fix_to_virt() will be located here.

ffc00000 ffc7ffff Guard region

ff800000 ffbfffff Permanent, fixed read-only mapping of the
firmware provided DT blob

So, I have no option but to NAK this change. Sorry.

You can find this documentation in the "Documentation" subdirectory.

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