From: Mark Lord <lkml@rtr.ca>
To: Robert Hancock <hancockr@shaw.ca>
Cc: Allen Martin <AMartin@nvidia.com>, Jeff Garzik <jeff@garzik.org>,
Tejun Heo <htejun@gmail.com>, Gabor Gombas <gombasg@sztaki.hu>,
linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org,
Kuan Luo <kluo@nvidia.com>, Peer Chen <pchen@nvidia.com>
Subject: Re: sata_nv + ADMA + Samsung disk problem
Date: Wed, 02 Jan 2008 23:14:02 -0500 [thread overview]
Message-ID: <477C610A.30805@rtr.ca> (raw)
In-Reply-To: <477C2A99.9010208@shaw.ca>
Robert Hancock wrote:
>
> What we're doing to enter legacy mode is essentially:
>
> -wait until ADMA status indicates IDLE bit set (max wait of 1 microsecond)
> -clear GO bit in control register
> -wait until status indicates LEGACY bit set (max wait of 1 microsecond)
>
> and to enter ADMA mode:
>
> -set GO bit in control register
> -wait until status indicates LEGACY bit cleared and IDLE bit set (max
> wait of 1 microsecond)
..
If there are outstanding TCQ/NCQ commands (any drive),
then this could take (much) longer to enter legacy mode,
as the ADMA engine will wait for them all to finish.
But for normal, "nothing outstanding" mode, it should be very quick.
Cheers
next prev parent reply other threads:[~2008-01-03 4:14 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-08 12:08 sata_nv + ADMA + Samsung disk problem Gabor Gombas
2007-08-14 9:30 ` Tejun Heo
2007-08-14 12:02 ` Gabor Gombas
2007-08-16 16:06 ` Gabor Gombas
2007-08-16 18:45 ` Jim Paris
2008-01-01 16:44 ` Gabor Gombas
2008-01-02 3:25 ` Tejun Heo
2008-01-02 4:03 ` Robert Hancock
2008-01-02 4:20 ` Robert Hancock
2008-01-02 4:25 ` Tejun Heo
2008-01-02 6:19 ` Jeff Garzik
2008-01-02 6:39 ` Robert Hancock
2008-01-02 6:55 ` Tejun Heo
2008-01-03 0:27 ` Robert Hancock
2008-01-02 17:23 ` Allen Martin
2008-01-02 18:57 ` Jeff Garzik
2008-01-02 23:23 ` Allen Martin
2008-01-03 0:21 ` Robert Hancock
2008-01-03 4:14 ` Mark Lord [this message]
2008-01-03 4:17 ` Mark Lord
2008-01-03 4:54 ` Robert Hancock
2008-01-03 15:44 ` Mark Lord
2008-01-03 15:47 ` Mark Lord
2008-01-03 21:13 ` Benjamin Herrenschmidt
2008-01-04 1:43 ` Robert Hancock
2008-01-04 5:51 ` Benjamin Herrenschmidt
2008-01-04 0:41 ` Allen Martin
2008-01-04 2:51 ` Robert Hancock
2008-01-08 0:10 ` Robert Hancock
2008-01-11 23:18 ` Gabor Gombas
2008-01-12 1:10 ` Robert Hancock
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