Message-ID: <45C79F60.50305@garzik.org>
Date: Mon, 05 Feb 2007 16:19:28 -0500
From: Jeff Garzik <jeff@garzik.org>
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To: Alan <alan@lxorguk.ukuu.org.uk>
CC: Mark Lord <lkml@rtr.ca>, Patrick Ale <patrick.ale@gmail.com>,
       linux-kernel@vger.kernel.org
Subject: Re: hdparm for lib_pata
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Alan wrote:
>> Userspace PIO mode changes are NOT a good idea,
> 
> I would disagree there, but they are not high priority. We do need to
> allow set_features/xfer but we need to snoop it and mode set properly
> around it. There are cases you want to control this, more so admittedly
> for DMA speeds.

*Bingo*

That's the entire reason why libata does not support hdparm changing 
modes, etc.:  there is a lot involved in allowing random SET FEATURES - 
XFER MODE commands from userspace.  In some cases you have to stop all 
traffic on ports B,C,D,... in order to change the speed on port A.

	Jeff


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