Re: [issue1240] sata dvdrom leads to interrupt livelock

["Simon 'corecode' Schubert" <corecode@xxxxxxxxxxxx>]

Matthew Dillon wrote:
>     Those BMSTAT bits aren't part of the standard at all (that I know of),
>     but they are the only way to be able to tell if an ATA device is
>     actually the source of an interrupt when multiple devices share the
>     same interrupt.

Yes, that's the busmaster interrupt status.  The problem is that the drive 
doesn't set the busmaster error, but instead only the ata status error.

>     On the face of it it does seem as though we should be able to return
>     1 if ATA_BMSTAT_INTERRUPT is set and either ATA_BMSTAT_ERROR is
>     set or ATA_BMSTAT_ACTIVE is clear.  It is unclear to me whether
>     we can safely clear the ACTIVE bit, though, which is what that
>     next ATA_IDX_OUTB() will do if we allow the ERROR + INTERRUPT case
>     through.  Then again, maybe we have to.  I just don't know.

You can't clear ACTIVE, it is readonly.  We'd have to abort the busmaster 
transaction, and that's where I don't know what to do.  I'll have to try 
and see.

cheers
  simon

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