On Wed, May 17, 2017 at 11:16 PM, Chris Packham
<[email protected]> wrote:
> On 18/05/17 06:18, Borislav Petkov wrote:
> One thing I would like confirmation on is is in_le32 -> ioread32 the
> correct change? I tossed up between ioread32 and readl. Looking at
> mv643xx_eth.c which supports both the MV643XX and Orion it's using readl
> so perhaps I should be using that.
There is no easy answer: on powerpc, readl is used for PCI,
while in_le32 is used for on-chip devices, so in_le32 is the
right one in principle. The main difference is that readl can
work with CONFIG_EEH on pseries, but in_le32 is cheaper.
On ARM and most other architectures, readl is used for both
PCI and on-chip devices, so that's what portable code tends
to use.
ioread32 is required to behave the same way as readl
on all __iomem pointers returned from ioremap(), but
is an extern function on powerpc and can be more
expensive when CONFIG_GENERIC_IOMAP is set.
I'd go with readl() in this case.
Arnd
