Messages in this thread | | | Date | Thu, 16 Aug 2007 14:39:25 +0200 | From | Zoltan Boszormenyi <> | Subject | Re: Bad CD disk disables IDE DMA |
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Bodo Eggert írta: > Michal Piotrowski <michal.k.k.piotrowski@gmail.com> wrote: > >> On 15/08/07, Zoltan Boszormenyi <zboszor@dunaweb.hu> wrote: >> > > >>> I noticed that a bad CD of mine makes DMA disabled: >>> > > [...] > >>> hda: cdrom_decode_status: error=0x40 { LastFailedSense=0x04 } >>> ide: failed opcode was: unknown >>> hda: DMA disabled >>> hda: ide_intr: huh? expected NULL handler on exit >>> hda: ATAPI reset complete >>> >>> Every time I put the said CD into to drive and DMA is on, I get the >>> above messages. >>> >> This might be intended. >> > > Maybe, and maybe only a certain effect might be intended. And maybe I can > help by asking these questions: > > 1) Does disabling DMA fix the seek errors, or does it hide them by the PIO > interfce not printing them? >
With DMA off no seek error occurs. When the transfer rate is limited to UDMA3 I get this:
hda: drive_cmd: status=0x51 { DriveReady SeekComplete Error } hda: drive_cmd: error=0x04 { AbortedCommand } ide: failed opcode was: 0xec
Note the difference: the error code is different and it knows the failed opcode as well. But DMA remains on. Can it be a bad 80w cable? I don't think so, considering that it doesn't occur for DVDs when using UDMA4...
> 2) If it does hide them, would filtering for seek errors be a sane thing to > do, or does the DMA engine (or HDD) behave badly on these errors, or > do bad-DMA devices report seek errors, too? > > 3) If it does not hide them, would re-enabling DMA on disk change be a > feasable workaround? > (proposed interface: use hdparm -d $num where $num = > 0, 1: as before > 3: DMA on, if switched off automatically, will be set to 2 > 2: DMA off, will be turned on (set to 3) on disk change) >
The automatic DMA re-enabling would be a good solution.
> 4) Does libata work well enough for making all effort put into that old > IDE layer be a waste of time? >
Unfortunately libata (or pata_amd) doesn't work very well on this machine, I tried to switch to libata for the CD drive but it lost the DVD-playing capability. It seems the error was that libdvdcss couldn't get the keys via the scd device. This is the main obstacle that stops me switching to Fedora 7 from FC6. I reported it some time ago but got no answer. Look for subject "DVD-playing, ide-cd vs scsi-cd drivers".
Best regards, Zoltán Böszörményi
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