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

From: Ansuel Smith
Date: Sat May 08 2021 - 18:51:46 EST

On Sat, May 08, 2021 at 07:50:44PM +0100, Russell King - ARM Linux admin wrote:
> 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.
> --
> RMK's Patch system:
> FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

Thanks a lot for the review and sorry for the mess. Just to make sure I
don't push a very wrong patch another time. ipq8064 require 0x300000 of
IO space if all 3 lines are used. From what I can read in the
documentation, the PCI I/O mapping section does have space and can be
expanded to ff0fffff without causing collision. So I have to update that
part and the IO_LIMIT to 0x2fffff. Tell me if I'm completely wrong and
again, thanks for the review.