Re: [PATCH] asm-generic: io: Fix ioread16/32be and iowrite16/32be
From: Michal Simek
Date: Fri Feb 08 2013 - 03:24:17 EST
2013/2/8 Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>:
> On Thu, Feb 7, 2013 at 3:18 PM, Michal Simek <michal.simek@xxxxxxxxxx> wrote:
>> Fix ioreadXXbe and iowriteXXbe functions which did
>> additional little endian conversion on native big endian systems.
>> Using be_to_cpu (cpu_to_be) conversions with __raw_read/write
>> functions have resolved it.
>> Signed-off-by: Michal Simek <michal.simek@xxxxxxxxxx>
>> CC: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
>> CC: Arnd Bergmann <arnd@xxxxxxxx>
>> CC: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>> CC: Will Deacon <will.deacon@xxxxxxx>
>> CC: linux-arch@xxxxxxxxxxxxxxx
> I have one question (see below). Apart from that:
> Acked-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>> -#define ioread16be(addr) be16_to_cpu(ioread16(addr))
>> +#define ioread16be(addr) __be16_to_cpu(__raw_readw(addr))
> Why did you change it to the __beX_to_cpu variant with underscores?
The question could be probably different. Why are they even defined?
I have grepped the kernel and all archs use these generic macros
include/linux/byteorder/generic.h:94:#define be32_to_cpu __be32_to_cpu
include/linux/byteorder/generic.h:106:#define be32_to_cpup __be32_to_cpup
include/linux/byteorder/generic.h:118:#define be32_to_cpus __be32_to_cpus
What about to remove them?
Back to you question. I can't remember particular reason for that maybe
just experience that __ versions should be the fastest kernel implementation.
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/