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Message-ID: <48998852.30603@ru.mvista.com>
Date: Wed, 06 Aug 2008 15:17:38 +0400
From: Sergei Shtylyov <sshtylyov@...mvista.com>
To: Sergei Shtylyov <sshtylyov@...mvista.com>
Cc: Alan Cox <alan@...rguk.ukuu.org.uk>,
Robert Hancock <hancockr@...w.ca>,
Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
James Bottomley <James.Bottomley@...senpartnership.com>,
ksummit-2008-discuss@...ts.linux-foundation.org,
linux-kernel <linux-kernel@...r.kernel.org>,
linux-ide <linux-ide@...r.kernel.org>
Subject: Re: Kernel Summit request for Discussion of future of ATA (libata)
and IDE
Hello, I wrote:
>>>>>> supported. I couldn't track down where that bit was actually
>>>>>> defined in the first place, all the way back to ATA-1 it seems to
>>>>>> be indicated as reserved. Actually, I'm not sure why the drive
>>>>>> cares in the first place, it would seem like a pure host
>>>>>> controller issue..
>>>>>>
>>>>> It goes back before IDE into the depths of the original compaq
>>>>> spec. When
>>>>> you have a device wired basically directly to the ISA bus
>>>>> (original IDE)
>>>>>
>>>> ISA has only 8/16-bit data bus, so it could not have mattered
>>>> there...
>>>
>>> Depends what a 32bit I/O looks like on the 16bit bus - timing wise.
>>>
>>
>> Two 16-bit reads at addresses 0x1x0 and 0x1x2 with the programmed
>> recovery time, IIRC... It's just occured to me that in case of the
>> 16-bit bus it should be how the drive treated the accesses at address
>> 0x1x2 with IOCS16 asserted that could have mattered. If it honored
>> them, 32-bit I/O could have worked even on a dumb ISA "controller",
>> if not -- no way (unless you really had *something* between the ISA
>> and the IDE cable).
>
> Oh, -IOCS16 is driven by device, not host. I give up then. :-)
>
OTOH, it definitely could work if the drive asserted it for the I/O
port 0x1x2 at least for the data transfer phase (and probably even if it
always asserted -IOCS16 for this address).
That pre-historic word indeed could have made sense then...
MBR, Sergei
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