Subject: Re: [PATCH 1/2] [IDE] Platform IDE driver

From: Sergei Shtylyov <[email-masked]>
Date: Wed, 25 Jul 2007 23:35:00 +0400

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