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From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
To: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Robert Hancock <hancockr@shaw.ca>,
	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
Date: Mon, 22 Dec 2008 23:16:36 +0300	[thread overview]
Message-ID: <494FF5A4.9010809@ru.mvista.com> (raw)
In-Reply-To: <494CF231.4020000@ru.mvista.com>

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

      reply	other threads:[~2008-12-22 20:16 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-12-18 14:18 [PATCH] ide: Fix ata_id_has_dword_io to return DWORD I/O support properly Mario Schwalbe
2008-12-18 17:08 ` Jeff Garzik
2008-12-18 17:24   ` Sergei Shtylyov
2008-12-18 20:42     ` Bartlomiej Zolnierkiewicz
2008-12-18 22:40       ` Alan Cox
2008-12-18 23:13         ` Bartlomiej Zolnierkiewicz
2008-12-19 10:50           ` Alan Cox
2008-12-19 19:30             ` Bartlomiej Zolnierkiewicz
2008-12-20  0:10               ` Alan Cox
2008-12-19 11:31         ` Sergei Shtylyov
2008-12-19 11:34           ` Sergei Shtylyov
2008-12-18 18:10   ` Alan Cox
2008-12-20  1:58     ` Robert Hancock
2008-12-20  1:58       ` Robert Hancock
2008-12-20 13:25       ` Sergei Shtylyov
2008-12-22 20:16         ` Sergei Shtylyov [this message]

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