Messages in this thread | | | Date | Wed, 14 Nov 2007 11:41:37 -0500 | From | Mark Lord <> | Subject | Re: libata/PATA: GPCMD_SET_STREAMING via SG_IO does nothing |
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Mark Lord wrote: > Sebastian Kemper wrote: >> Hi Alan! >> >> On Tue, Nov 13, 2007 at 09:22:30PM +0000, Alan Cox wrote: >>> 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. >>> >>> Do you have a simple code example that shows the problem ? >> >> http://svn.mplayerhq.hu/mplayer/trunk/stream/stream_dvd.c?view=markup > .. > > That code is riddled with bugs, by the way. > It fails to close/clean-up on just about every exit path. > But apart from that, it does appear to issue the command. > > Another way to the same thing is with "hdparm -E", > which contrary to my earlier posting actually does > seem to work already with libata. > >> See dvd_set_speed(). The drive I'm using is an Optiarc DVD RW AD-7170A. >> With the "old" ATA driver dvd_set_speed() works, with libata it doesn't. > .. > > Can you define "doesn't work" for me? > How can I test this to see if it works one way or another ? > > The command issue (ioctl) is not returning -1. ..
Ahh.. got it. The host_status returned (not checked by that code) was 7, which means "host error".
In this case, that's because the cmd_len is (16), which is too large for ATAPI. It needs to be changed to (12) instead.
So this line: sghdr.cmd_len = 12; The code (apart from totally mishandling any kinds of errors) works after that.
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