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Message-ID: <46A7A5E4.4090105@ru.mvista.com>
Date: Wed, 25 Jul 2007 23:35:00 +0400
From: Sergei Shtylyov <sshtylyov@...mvista.com>
To: Scott Wood <scottwood@...escale.com>
Cc: Vitaly Bordug <vitb@...nel.crashing.org>,
linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org,
linuxppc-dev@...abs.org
Subject: Re: [PATCH 1/2] [IDE] Platform IDE driver
Scott Wood wrote:
>>> It doesn't buy us anything in here, but it's conceivable that someone
>>> may want to write a driver that uses a shift in the I/O accessor
>>> rather than an array of port offsets,
>> It wouldn't be IDE driver then, and neither it would be libata
>> which also does this another way this (despite pata_platform uses
>> shifts too -- not in the accessors, so no speed loss).
> The device tree is not just for Linux.
Yeah, and I can't wait to see some other its users. ;-)
This doesn't mean that shift is better anyway. If everyone considers it
better, I give up. But be warned that shift (stride) is not the only property
characterizing register accesses -- the regs might be only accessible as
16/32-bit quantities, for example (16-bit is a real world example -- from
Amiga or smth of that sort, IIRC).
>>> equivalent of the cntlzw innstruction, and shift makes it clear that
>>> the stride must be power-of-two). Plus, using shift is consistent
>>> with what we do on ns16550.
>> Why the heck should we care about the UART code taling about IDE?!
> Consistency?
We're not obliged to be consistent with every piece of the kernel code.
> -Scott
MBR, Sergei
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