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SubjectRe: More data on ide-cd "playing music" death
"Andre M. Hedrick" wrote:
> I can/have reproduce the report and was about to bug you also.
> A little more datails........there are only problems if the drive tries to
> run in UDMA mode period........this may also react the same way if DMA is
> enabled regardless of mode...........

Alright, I hadn't noticed this.

> Part of this may be in the raw ide-driver, since I get additional reports
> of "lost interrupts". Since the problems go away if I force transfer
> rates to a PIO level, there is a combination problem IMHO......now where
> to start if there are two potential overlapping bugs????

That is my theory, as the problems do seem to arise from the ide code.
If
disabling DMA for the CD works now, I think we should start there.

> At one point in time........there was a cd-speed-something tool?
> Should we consider a pyramid stepping rate to begin transfers while
> slowing increasing spindle rates to prevent timeouts? Or propose a table
> of timeouts that are scaled to the max speed of the cdrom and adjust for
> interrupt ide_wait commands?

We don't really have a final say in how fast the CD-ROM decides to
transfer data. But according to the ATAPI standard the drive may only
select a _slower_ speed than requested. Either way, your second
proposal sounds more like the way to do it, IMO.

--
* Jens Axboe
*
* "The only thing that interferes with my
* learning is my education." -- A. Einstein

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