Re: [PATCH 1/2] ide: Add tx4939ide driver

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello.

Atsushi Nemoto wrote:

>>>>   This doesn't look consistent (aside from the TX4939IDE_REG8/16 issue) 
>>>>-- mm_outsw_swap() calls cpu_to_le16() before writing 16-bit data but 
>>>>this code doesn't. So, either one of those should be wrong...
>>>
>>>Thanks, this code should be wrong.  IDE_TFLAG_OUT_DATA is totally
>>>untested...
>>
>>   Hum, not necessarily...
>>   If the data register is BE, this should work correctly, if I don't 
>>mistake (once you fix the data register's address).

> Hmm... or ide_tf_load()/ide_tf_read() is broken for big endian MIPS ?
> (and possibly SPARC etc.)

> __ide_mm_writesw(port, &data, 1) should be used instead of writew()
> for IDE_TFLAG_OUT_DATA?

    Probably the code there relies on the writew() doing the necessary byte 
swapping -- the same as ata_{in|out}_data() must be reying on ins[wl]() and 
outs[wl]() to do that, as well as on __ide_mm_reads[wl]() and 
__ide_mm_writes[wl]() -- which boil down to reads[wl]() and writes[wl]() on MIPS.
    What's not clear to me is why in MIPS read[wlq]() vs reads[wlq](), 
write[wlq]() vs writes[wl], in[wlq]() vs ins[wlq](), and out[wlq]() vs 
outs[wlq]() are using the different byte swapping: the single form uses 
ioswab[wlq]() while the sting form uses __mem_ioswab[wlq]() -- and those are 
defined as one swapping bytes and the other not in 
incluse/asm-mips/mach-generic/mangle-port.h. Cananybody shed some light on this?

> ---
> Atsushi Nemoto

MBR, Sergei