Messages in this thread | | | Date | Wed, 29 Mar 2000 14:24:50 -0500 (EST) | From | Mike Porter <> | Subject | Re: The 2.3.x Job List (Updated) |
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On Tue, 28 Mar 2000, Alan Cox wrote:
> > > > Use PCI DMA 'lost interrupt' problem with some hw [which ?] > > > > > > wow ! > > > I do have 'Use PCI DMA' in my 2.2.15pre14 > > > and I do get 'lost interrupt' when trying to restore data from > > > my ide-tape OnStream 30Go. of course it doesn't work. > > > > > > I have to try disabling 'Use PCI DMA' though. > > > > > > > > > So your answer could include 'OnStream 30Go ide-tape' > > > > The OnStream DI-30 runs flawless in PIO or DMA mode. > > Then why are people seeing lost interrupts ? > > Right at the moment I suspect most of the lost interrupt stuff is PCI/APIC > stuff, certainly on 2.3.9x. You can't simply say 'it runs flawlessly' when > for someone it doesn't.
Whelp, this has been fun. I reported eariler that I was able to get rid of the DMA timeouts by setting udma mode 0. I tried this based on a completely flawed assumption.
The assumtion was that the values reported for tDMA in hdparm have anything to do with udma modes. They do not - they are used to set timings for multiword DMA modes (I don't have the Intel and ATAPI-5 spec here today, so I'm not writing precisely.)
At least on the PIIX4, there are very few parameters that have anything to do with UDMA. The CT values, which of course set the UDMA mode and some other flags which I'm not sure if they even effect UDMA. Specically PPE, DTE and TIME. IORDY also, but use of IORDY is clearly linked to some features of the ATAPI drive. Deciding whether or not it should be set is pretty easy.
And that's about it. There just isn't all sorts of magic needed.
I was reading the ATAPI-5 spec, and it talks about the use of an 80 wire cable when the PCB trace length is "long". This led me to the idea that if my drive or motherboard was somewhat out of spec, perhaps the better grounding supplied by the 80 wire cable would help. Perhaps the IDE cables are running too close to the SCSI cables. Maybe all the fans spinning in the case slam too many electrons into photons affecting subspace.
Using the 80 wire cable allows UDMA/33 to work with my ASUS P2B-DS and my Seagate ST39140A. Please note that the cable I took out was most likely the cable that came with the Seagate. It is 18", with two drive connectors about 6" apart. The ending connector was attached to the drive.
This is on kernel 2.2.15pre14, with the ide patch from a few days ago applied.
Perhaps we need a way to change the IDE controller's mode? Similar to how hdparm can cause the features (transfer mode) of the IDE device to be changed.
Mike
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