Re: [RFT PATCH v3 12/27] of/address: Add infrastructure to declare MMIO as non-posted

[Arnd Bergmann]

On Mon, Mar 8, 2021 at 10:14 PM Rob Herring <robh@xxxxxxxxxx> wrote:
> On Mon, Mar 08, 2021 at 09:29:54PM +0100, Arnd Bergmann wrote:
> > On Mon, Mar 8, 2021 at 4:56 PM Rob Herring <robh@xxxxxxxxxx> wrote:
>
> Let's just stick with 'nonposted-mmio', but drop 'posted-mmio'. I'd
> rather know if and when we need 'posted-mmio'. It does need to be added
> to the DT spec[1] and schema[2] though (GH PRs are fine for both).

I think the reason for having "posted-mmio" is that you cannot properly
define the PCI host controller nodes on the M1 without that: Since
nonposted-mmio applies to all child nodes, this would mean the PCI
memory space gets declared as nonposted by the DT, but the hardware
requires it to be mapped as posted.

       Arnd