Re: [PATCH] arm64: dts: marvell: armada-37xx: Remap IO space to bus address 0x0

Arnd Bergmann
2022-02-19T21:02:38Z

On Sat, Feb 19, 2022 at 12:34 PM Marek Behún <kabel@kernel.org> wrote:
>
> On Fri, 18 Feb 2022 22:25:26 +0100
> Pali Rohár <pali@kernel.org> wrote:
>
> > Remap PCI I/O space to the bus address 0x0 in the Armada 37xx
> > device-tree in order to support legacy I/O port based cards which have
> > hardcoded I/O ports in low address space.
> >
> > Some legacy PCI I/O based cards do not support 32-bit I/O addressing.
> >
> > Since commit 64f160e19e92 ("PCI: aardvark: Configure PCIe resources from
> > 'ranges' DT property") this driver can work with I/O windows which have
> > a different address for CPU than for PCI bus (unless there is some
> > conflict with other A37xx mapping), without needing additional support
> > for this in the firmware.
> >
> > Note that DDR on A37xx is mapped to bus address 0x0 and that mapping of
> > I/O space can be set to address 0x0 too because MEM space and I/O space
> > are separate and so they do not conflict.
> >
> > Signed-off-by: Pali Rohár <pali@kernel.org>
> > Reported-by: Arnd Bergmann <arnd@arndb.de>
>
> Reviewed-by: Marek Behún <kabel@kernel.org>

Reviewed-by: Arnd Bergmann <arnd@arndb.de>