On Thu, Mar 4, 2021 at 10:40 PM Hector Martin [off-list ref] wrote:

This implements the 'nonposted-mmio' and 'posted-mmio' boolean
properties. Placing these properties in a bus marks all child devices as
requiring non-posted or posted MMIO mappings. If no such properties are
found, the default is posted MMIO.

of_mmio_is_nonposted() performs the tree walking to determine if a given
device has requested non-posted MMIO.

of_address_to_resource() uses this to set the IORESOURCE_MEM_NONPOSTED
flag on resources that require non-posted MMIO.

of_iomap() and of_io_request_and_map() then use this flag to pick the
correct ioremap() variant.

This mechanism is currently restricted to Apple ARM platforms, as an
optimization.

Signed-off-by: Hector Martin <redacted>

This is fine with me atleast given that the nonposted IO is acceptable.
Caching the quirk state in a static local is maybe a bit overoptimized
but if the compiler can't see it but we can, why not.
Reviewed-by: Linus Walleij <redacted>

Yours,
Linus Walleij