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SubjectRe: [PATCH] CDROM: replace jiffies busyloop with msleep
On 05/22/2007 12:25 PM, Thomas Gleixner wrote:

> From: Ingo Molnar <mingo@elte.hu>
>
> The SJCD driver uses a jiffies busy loop. Replace it with msleep.
>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> Acked-by: Thomas Gleixner <tglx@linutronix.de>

Okay, that's just waiting for a reset to complete, which seems perfectly
fine with a sleeping loop like that, but...

I re-started working on a rewrite of the mitsumi legacy cdrom driver that
Pekka Enberg and I have been doing this afternoon again and I ran into not
being able to use sleeping loops there an hour ago!

The trouble there is that unless you poll the bloody thing like mad too much
of the Q subchannels passes below you and you need a huge number of retries
to get anything out of it. I noticed when I started adding audio bits that
the driver took full seconds to complete some audio requests while the old
driver was snappy in that regard. When I replaced our sleeping loop with a
busy-wait same as the original the snappyness returned and moreover, reading
the TOC from the CD went from something close to a minute to approximately a
second. Thought that minute was just because I was dealing with an old junk
1-speed drive...

Now, as said, this looks to be fine since it's just waiting for a reset to
complete, but unless you have the hardware to actually test, be careful in
there.

Or in fact, maybe even decide there's not much point. The current plan is to
do mitsumi, sony and panasonic and then throw the rest away (that trio is
special in so far that controllers for them are still available on a lot of
old ISA soundcards). Or do you actually have the hardware?

Rene.
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