Re: Re: Is controlling DVD speeds via SET_STREAMING supported?

[Jens Axboe]

On Wed, Nov 24 2004, Thomas Fritzsche wrote:
> Hi David,
> 
> I had the same problem with my DVD+-RW NEC-ND 3500 (NEC-support told me
> that they didn't support linux :-( ). After googling I couldn't find an
> answer. Because I didn't know anything about ide-cd (yesterday ;-))  I
> read in this spec about the SET STREAMING command:
> ftp://ftp.avc-pioneer.com/Mtfuji_4/Spec/Fuji4r10.pdf
> If you also read the newer Specs (Mtfuji_5) then you'll find out that the
> "SET CD SPEED" command is "only applicable to CD-R/RW logical units".
> It looks like older DVD-Drives also support this command, but newer do not
> support this for DVD+-R. But there is also the SET STREAMING command as
> Jens Axboe described on this list. Not all devices support this feature
> but my NEC-CD 3500 does (as I found out ;-) / my Teac-CD-RW does not)
> 
> I wrote a little programm to test this SET STREAMING command (quick &
> dirty). In my opinion it would make sence to also enhance the kernel
> function cdrom_select_speed (linux/drivers/ide/ide-cd.c), so that this
> function works also for "newer" DVD-drives.
> (!first check for the Realtime-Streaming-Feature and then use the right
> command to set the speed). Because DVD+-RW Drives will be faster (AND
> LOUDER!!) very soon it would be nice to have this in the kernel.

I agree, I'll do a patch for this right now. Your example code looks
fine. My only worry is that some drives might complain if your end_lba
is larger than the capacity, I'll have to double check the spec.

-- 
Jens Axboe

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