Date: Tue, 13 Nov 2007 21:22:30 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Sebastian Kemper <sebastian_ml@gmx.net>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: libata/PATA: GPCMD_SET_STREAMING via SG_IO does nothing
Message-ID: <20071113212230.77cadecd@the-village.bc.nu>
In-Reply-To: <20071113164323.GA5252@section-eight>
References: <20071113164323.GA5252@section-eight>
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> while trying to limit the speed of DVD drives during DVD playback I've
> come under the impression that GPCMD_SET_STREAMING via SG_IO doesn't yet
> work with libata/PATA (AMD/NVIDIA PATA support). I tested on an NForce2
> board (all IDE, no SATA) and kernel 2.6.22.12. When I use the "old" ATA
> kernel driver my drive slows down, with libata it doesn't. Is this a
> known issue or has this slipped by unnoticed?

It isn't a known issue, and it suprises me as SG_IO basically passes
commands through to the drive. We don't support speed change via xfermode
setting but GPCMD_SET_STREAMING sohuld behave.

> 
> I tried with mplayer dvd:// -dvd-device /dev/sr0 -dvd-speed BTW . I get
> no errors in syslog/dmesg. Also mplayer doesn't report a problem (so
> ioctl(fd, SG_IO, &sghdr) doesn't have a return < 0).

Do you have a simple code example that shows the problem ?
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