Re: libata/PATA: GPCMD_SET_STREAMING via SG_IO does nothing

From: Alan Cox
Date: Tue Nov 13 2007 - 16:23:22 EST


> 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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