Date: Mon, 21 May 2007 12:15:37 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Tejun Heo <htejun@gmail.com>
Cc: Robert Hancock <hancockr@shaw.ca>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       ide <linux-ide@vger.kernel.org>, l.genoni@oltrelinux.com
Subject: Re: something strange in libata-core.c for kernel 2.6.22-rc3
Message-ID: <20070521121537.48dd2b2c@the-village.bc.nu>
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> Yeah, that's consistent to what I've seen on my machine which is a
> variant of A8N.  No matter what value I through at _STM, _GTM just
> echoed the result thus always leading to 80c configuration.
> 
> > I guess this means that what we have to do is trust that the BIOS set up
> > a reasonable mode and base the cable detect on that (either by reading
> > back the boot-up controller registers, or by calling GTM). I imagine
> > this is what the Windows default IDE driver is doing (just using the
> > boot-up mode and feeding it back using GTM/STM on suspend/resume cycles).
> 
> Alan, what do you think?

Interesting, sounds like it is still useful rather than just reading the
registers as the GTM/STM seem to survive resume cycles which drive config
may not (eg if the driver is loaded after a s2ram/resume.

If it just echoes back we should also be able to detect this by using
knowingly invalid values.

Alan
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