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Message-ID: <494FF5A4.9010809@ru.mvista.com>
Date: Mon, 22 Dec 2008 23:16:36 +0300
From: Sergei Shtylyov <sshtylyov@...mvista.com>
To: Sergei Shtylyov <sshtylyov@...mvista.com>
Cc: Robert Hancock <hancockr@...w.ca>, linux-ide@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ide: Fix ata_id_has_dword_io to return DWORD I/O support
properly
Hello, I 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...
The 8-bit cycles would be at ports 0x1x2 and 0x1x3, of course. :-)
MBR, Sergei
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