Re: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with ioread32/iowrite32

From	Arnd Bergmann <arnd@arndb.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with ioread32/iowrite32
Date	2017-05-17 23:50 +0200
Message-ID	<tIeZr-8x-5@gated-at.bofh.it> (permalink)
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On Wed, May 17, 2017 at 11:16 PM, Chris Packham
<Chris.Packham@alliedtelesis.co.nz> 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

Thread

[PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with ioread32/iowrite32 Chris Packham <chris.packham@alliedtelesis.co.nz> - 2017-05-12 06:30 +0200
  Re: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with  ioread32/iowrite32 Borislav Petkov <bp@alien8.de> - 2017-05-17 20:20 +0200
    Re: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with  ioread32/iowrite32 Chris Packham <Chris.Packham@alliedtelesis.co.nz> - 2017-05-17 23:20 +0200
      Re: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with ioread32/iowrite32 Arnd Bergmann <arnd@arndb.de> - 2017-05-17 23:50 +0200
        RE: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with  ioread32/iowrite32 David Laight <David.Laight@ACULAB.COM> - 2017-05-19 16:10 +0200
          Re: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with ioread32/iowrite32 Arnd Bergmann <arnd@arndb.de> - 2017-05-19 17:30 +0200
      Re: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with  ioread32/iowrite32 Borislav Petkov <bp@alien8.de> - 2017-05-18 10:10 +0200
    Re: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with ioread32/iowrite32 Michael Ellerman <mpe@ellerman.id.au> - 2017-05-18 07:40 +0200
      Re: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with ioread32/iowrite32 Arnd Bergmann <arnd@arndb.de> - 2017-05-18 13:10 +0200
        Re: [PATCH 3/3] EDAC: mv64x60: replace in_le32/out_le32 with ioread32/iowrite32 Michael Ellerman <mpe@ellerman.id.au> - 2017-05-19 12:00 +0200

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