Messages in this thread | | | Date | Mon, 17 Sep 2007 07:00:03 +0200 | From | Tejun Heo <> | Subject | Re: [PATCH 1/1] pata_it821x: fix lost interrupt with atapi devices |
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[cc'ing Albert and linux-ide]
Alan Cox wrote: > /from the media. */ >> > + if (qc->nbytes < 2048) >> > + return -EOPNOTSUPP; >> > + >> > /* No ATAPI DMA in smart mode */ >> > if (itdev->smart) >> > return -EOPNOTSUPP; >> > >> >> This looks like a gross hack. Aren't you supposed to inspect >> the command instead and whitelist the ones you know are OK, >> like pata_pdc2027x.c and sata_promise.c do? > > It does seem to be about transfer size in the IT821x case not commands. > It may be to do with how we issue ATAPI command transfer sizes from high > up (patch went to Jeff) but for now this is definitely the right approach > > Reviewed-by: Alan Cox <alan@redhat.com>
I wonder whether we should be using similar check in generic path too. We have quite a few cases where MWDMA ATAPI devices choking on commands with small transfer sizes. I don't think we'll experience significant performance regression with this applied and even if there is some, it's far better to have slightly slower working device.
What do you guys think?
-- tejun
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