Re: [PATCH] RFC: ptp: add comment about register access race

[Arnd Bergmann]

On Tue, Mar 4, 2025, at 05:09, Richard Cochran wrote:
> On Mon, Mar 03, 2025 at 09:50:01AM +0200, Andy Shevchenko wrote:
>> Perhaps it's still good to have a comment, but rephrase it that the code is
>> questionable depending on the HW behaviour that needs to be checked.
>
> IIRC both ixp4xx and the PCH are the same design and latch high reg on
> read of low.

Ok, if that's a common thing, let's assume that the drivers are
all correct for the respective hardware and discard my patch.

With the patch I have queued up in the asm-generic tree, the
behavior changes so ioread64_lo_hi() no longer gets turned
into a single 64-bit access, and that is then more likely to
be correct for both 32-bit and 64-bit architectures in case the
device doesn't actually implement 64-bit transactions but does
correctly latch the contents.

      Arnd