Messages in this thread | | | Date | Wed, 06 Feb 2013 18:40:56 +0100 | From | Michal Simek <> | Subject | Re: [PATCH] drivers/block/xsysace - replace in(out)_8/in(out)_be16/in(out)_le16 with generic iowrite(read)8/16(be) |
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On 02/07/2013 01:34 AM, Arnd Bergmann wrote: > On Wednesday 06 February 2013 17:21:37 Michal Simek wrote: > >> I have looked at the patches from more practical side and I have tested it on >> microblaze big endian in 16bit mode and I have found that sysace driver >> stop to work. >> After that I have looked at ioread/iowrite microblaze implementation >> and implementation of that functions is wrong. >> I have fixed it but looking at using asm-generic/io.h for microblaze. >> >> I will do more tests and let you know. > > Well, I think they are only wrong in the way that they ignore > endianess. You can fix that by changing them to be identical > to the in_le/in_be families.
But still it is wrong.
> > However, I would also recommend changing your __raw_* accessors > to inline assembly functions rather than pointer dereferences, > because we have had problems in the past where gcc (when faced > with undefined C) silently turned 32-bit accesses into multiples > of byte accesses, which can be fatal for MMIO. The asm-generic > version obviously cannot get this right. > > The PCI I/O space handling, as mentioned, is completely broken > on microblaze, and you can either use the approach from asm-generic > when you set PCI_IOBASE match your isa_io_base.
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)
On little be16_to_cpu(v) is swab16(v) and __cpu_to_le16(swab(b)) is swab16(v)
What I would expect is #define iowrite16be(v, addr) __raw_writew(__cpu_to_be16(v), addr)
on Big endian: __cpu_to_be16(v) is (v) on Little endian: __cpu_to_be16(v) is swab(v)
What am I missing here?
Thanks, Michal
-- Michal Simek, Ing. (M.Eng) w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/ Microblaze U-BOOT custodian
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