Re: readcd hangs in blk_execute_rq

[Meelis Roos]

> > Turned DMA off with hdparm -d 0 /dev/hdc, still the same.
> > Turned ATAPI DMA support off completely (activated "Use DMA only for
> > disks" compile option), still the same half-hang.
>
> Can I talk you into trying to find out when this broke? You mention
> 2.4.18 as working, did 2.4.19 break? Narrowing this down as much as
> possible would be very helpful.

OK, did some testing.

2.4.18, 2.4.19 and 2.4.20 are the same - mostly working. This means that
it reads non-broken data CD-s with DMA with no problems, but it loses an
interrupt and disables DMA with a faulty data CD (dmesg below).

The IDE changes in 2.4.21-pre1 cause DMA to fail at first read attempt
and all later kernels behave the same.

The dmesg from 2.4.18 in case of CD read error (with a known faulty cd):

hdc: command error: status=0x51 { DriveReady SeekComplete Error }
hdc: command error: error=0x54
end_request: I/O error, dev 16:00 (hdc), sector 1274020
ide_dmaproc: chipset supported ide_dma_lostirq func only: 13
hdc: lost interrupt
hdc: status timeout: status=0xd0 { Busy }
hdc: DMA disabled
hdc: drive not ready for command
hdc: ATAPI reset complete


-- 
Meelis Roos (mroos@xxxxxxxx)

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