On Mon, 8 Feb 2016 17:30:50 +0000 Brian Starkey <brian.star...@arm.com> wrote:
> Add a flag to memremap() for writecombine mappings. Mappings satisfied
> by this flag will not be cached, however writes may be delayed or
> combined into more efficient bursts. This is most suitable for
> buffers written sequentially by the CPU for use by other DMA devices.
>
> ...
The patch generally looks OK to me. It generates rejects against
linux-next because of some janitorial changes in memremap.c.
> @@ -101,6 +107,11 @@ void *memremap(resource_size_t offset, size_t size,
> unsigned long flags)
> addr = ioremap_wt(offset, size);
> }
>
> + if (!addr && (flags & MEMREMAP_WC)) {
> + flags &= ~MEMREMAP_WC;
> + addr = ioremap_wc(offset, size);
> + }
> +
> return addr;
> }
The modifications of `flags' is unneeded (and the compiler will remove
it). And generally the modification of incoming args is a bit nasty
IMO - I find it's better to treat them as const - part of the calling
environment which can be relied upon to be unaltered as the code
evolves.
