# Re: \[RFT PATCH v3 08/27\] asm-generic/io.h: Add a non-posted variant of ioremap()

- From: Andy Shevchenko \<hidden\>
- Date: 2021-03-05 14:47:21 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2021/03/6290036
- Thread: https://ratatoskr.run/linux-arm-kernel/2021/03/6288800/t.md

```text
On Thu, Mar 4, 2021 at 11:40 PM Hector Martin [ref] wrote:
>
> ARM64 currently defaults to posted MMIO (nGnRnE), but some devices
> require the use of non-posted MMIO (nGnRE). Introduce a new ioremap()
> variant to handle this case. ioremap_np() is aliased to ioremap() by
> default on arches that do not implement this variant.

Hmm... But isn't it basically a requirement to those device drivers to
use readX()/writeX() instead of readX_relaxed() / writeX_relaxed()?

...

>  #define IORESOURCE_MEM_32BIT           (3<<3)
>  #define IORESOURCE_MEM_SHADOWABLE      (1<<5)  /* dup: IORESOURCE_SHADOWABLE */
>  #define IORESOURCE_MEM_EXPANSIONROM    (1<<6)
> +#define IORESOURCE_MEM_NONPOSTED       (1<<7)

Not sure it's the right location (in a bit field) for this flag.

-- 
With Best Regards,
Andy Shevchenko

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