Messages in this thread | | | Date | Wed, 19 Apr 2006 08:35:22 -0700 | From | "James Ausmus" <> | Subject | Re: [PATCH 1/1] ide: Allow disabling of UDMA for Compact Flash devices |
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On 4/18/06, Robert Hancock <hancockr@shaw.ca> wrote: > James Ausmus wrote: > > This is exactly the situation that I have with 2 separate "dumb" (just > > physical interfaces, essentially - not at all detectable) IDE->CF > > adapters - both the IDE controller and the CF media support several > > UDMA modes, so the IDE driver throws the CF device into UDMA mode on > > bootup. However, as the physical interface between the IDE cable and > > the CF socket is poorly engineered, it cannot handle the higher > > speeds, causing the timeout errors. For some people, this can just be > > fixed with an ide=nodma boot option, but as I also have a (quite > > large) rotating media device on the controller, this is not an option, > > as, if a fsck is performed on a boot, the boot-up time is upwards of > > 30 minutes. > > If it's like some of the CF-IDE adapters I've seen, the DMA request/ack > lines likely aren't even wired up between the card and the cable. > There's no way the kernel can detect that DMA is not actually possible > on such a card without trying and waiting for it to timeout. (I've seen > a few which have jumpers which select whether to connect these or not - > haven't a clue why you wouldn't want to hook those up unconditionally..) > > Isn't there an option to disable DMA for a specific IDE channel > (ide2=nodma or something like that)? >
Yes, there is, but that unfortunately does not solve the issue for configurations where there is also a UDMA capable device on the same channel. If there was something like ide2=0:nodma,1:dma or some such, in order to enable/disable dma on a per device basis, instead of a per-channel basis, then that would also solve the issue.
-James
> -- > Robert Hancock Saskatoon, SK, Canada > To email, remove "nospam" from hancockr@nospamshaw.ca > Home Page: http://www.roberthancock.com/ > > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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