Messages in this thread | | | Date | Thu, 7 Feb 2013 08:23:41 +0100 | Subject | Re: [PATCH] drivers/block/xsysace - replace in(out)_8/in(out)_be16/in(out)_le16 with generic iowrite(read)8/16(be) | From | Michal Simek <> |
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2013/2/6 Geert Uytterhoeven <geert@linux-m68k.org>: > On Wed, Feb 6, 2013 at 6:40 PM, Michal Simek <monstr@monstr.eu> wrote: >> One question regarding to asm-generic/io.h about iowrite16be implementation >> >> #define iowrite16be(v, addr) iowrite16(be16_to_cpu(v), (addr)) >> #define iowrite16(v, addr) writew((v), (addr)) >> #define writew(b,addr) __raw_writew(__cpu_to_le16(b),addr) >> >> static inline void __raw_writew(u16 b, volatile void __iomem *addr) >> { >> *(volatile u16 __force *) addr = b; >> } >> >> How is this suppose to work on Big Endian? >> be16_to_cpu(v) is (v) >> and >> __cpu_to_le16(b) is swab16(v) > > Yes.
But on native BE system ( I expect that v is in big endian) iowrite16be(v, addr) should be just *(volatile u16 __force *) addr = v; not *(volatile u16 __force *) addr = swab16(v);
>> On little >> be16_to_cpu(v) is swab16(v) > > Yes. > >> and >> __cpu_to_le16(swab(b)) is swab16(v) > > ??? > > Don't you mean "__cpu_to_le16(b) is (b)"?
BTW: I took output value from the first line (be16_to_cpu(v) is swab16(v))
Grrr - on LE this code works. (I expect that v is in little endian) iowrite16be(v, addr) is *(volatile u16 __force *) addr = swab16(v);
>> What I would expect is >> #define iowrite16be(v, addr) __raw_writew(__cpu_to_be16(v), addr) > > Indeed, it should be "__cpu_to_be16(v)" instead of "be16_to_cpu(v)".
What do you mean by that?
Thanks, Michal
-- 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
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