Message-ID: <494CF231.4020000@ru.mvista.com>
Date: Sat, 20 Dec 2008 16:25:05 +0300
From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
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To: Robert Hancock <hancockr@shaw.ca>
Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ide: Fix ata_id_has_dword_io to return DWORD I/O   support
 properly
References: <494A5BBF.8000807@inf.tu-dresden.de>	<494A837A.50801@garzik.org> <20081218181015.2e160d5c@lxorguk.ukuu.org.uk> <494C512B.6090304@shaw.ca>
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Hello.

Robert Hancock wrote:

>>> This seems like a risky assumption...
>>
>> Its wrong on various counts
>>
>> - ata_id_major_version can't tell early ATA versions apart
>> - on anything later than the early ISA IDE paddles (the ones that
>> basically were just bus decoders) its invisible to the drive
>>
>> Except for legacy ISA bus controllers (and even there it is 
>> questionable)
>> I would favour simply ignoring it.
>
> 32-bit IO wouldn't work on any ISA controller, would it? What happens 
> if you do 32-bit IO port access on something on the ISA bus?

   TTBOM, depending on what's driven by device on -IOCS16, this will 
translate into 2, 3, or 4 cycles at the successive addresses. In case of 
the IDE data register, this should translate into one 16-bit cycle at 
0x1x0, one 8-bit cycle at 0x1x1, and one 8-bit cycle at 0x1x2 which is 
of course not what anybody would want...

WBR, Sergei


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