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Message-ID: <alpine.LFD.1.00.0803161238190.3020@woody.linux-foundation.org>
Date: Sun, 16 Mar 2008 12:39:43 -0700 (PDT)
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Alan Cox <alan@...rguk.ukuu.org.uk>
cc: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
Anders Eriksson <aeriksson@...tmail.fm>,
"Rafael J. Wysocki" <rjw@...k.pl>,
Jens Axboe <jens.axboe@...cle.com>,
Ingo Molnar <mingo@...e.hu>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Linux 2.6.25-rc4
On Sun, 16 Mar 2008, Alan Cox wrote:
>
> No it doesn't. DRQ simply means "drive has more data for the controller
> if you want it". Interrupts are controlled via IEN and the interrupt line.
A _lot_ of chips require you to clear the DRQ by taking the data they
have.
> If the drive wants to give us data and we end the transaction that is
> fine. In practice a tiny few devices crap themselves if we don't.
More than a few tiny devices from what I remember. It tends to be the
other way around - most devices do *not* want to get new commands until
you've finished the previous one by draining the queues.
Linus
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