> From: Hector Martin
> Date: Wed, 10 Feb 2021 21:24:15 +0900
Hi Hector,
Since device tree bindings are widely used outside the Linux tree,
here are some thoughts from a U-Boot and OpenBSD perspective.
> Hi Will, I'm pulling you in at Marc's suggestion. Do you have an opinion
> on what the bet
Hi Will, I'm pulling you in at Marc's suggestion. Do you have an opinion
on what the better solution to this problem is?
The executive summary is that Apple SoCs require nGnRnE memory mappings
for MMIO, except for PCI space which uses nGnRE. ARM64 currently uses
nGnRE everywhere. Solutions dis
On 09/02/2021 18.15, Arnd Bergmann wrote:
Right, these are the same ranges that I found in the adt and that Mark
listed in his code snippet, so it seems we all see the same partitioning
of the address space. I also see them reflected in the
/defaults/pmap-io-ranges property in ADT, which seems to
> From: Arnd Bergmann
> Date: Tue, 9 Feb 2021 10:15:31 +0100
>
> On Tue, Feb 9, 2021 at 1:25 AM Hector Martin wrote:
> > On 09/02/2021 08.20, Mark Kettenis wrote:
> > I probed writing to i<<28 for i = [0..255], using nGnRE. This reveals
> > that nGnRE writes are allowed (i.e. either succeed or e
On 09/02/2021 08.20, Mark Kettenis wrote:
It is only PCI mmio space that needs to be nGnRE. The PCI host
controller register space itself needs nGnRnE just like all other
integrated peripherals (or at least it works that way).
This is correct. Actually, as I just discovered, nGnRE writes to MM
> From: Arnd Bergmann
> Date: Mon, 8 Feb 2021 23:57:20 +0100
>
> On Thu, Feb 4, 2021 at 9:39 PM Hector Martin wrote:
>
> > (3) Do it at a lower level, in ioremap() itself. This requires that
> > ioremap() somehow discriminates based on address range to pick what
> > kind of mapping to m
This follows from the fixmap patch, but relates to the general case.
This is a hack, and incomplete. Read on for discussion.
The problem: on Apple ARM platforms, SoC MMIO needs to use nGnRnE
mappings: writes using nGnRE are blackholed. This seems to be by design,
and there doesn't seem to be any f
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