Messages in this thread | | | Date | Fri, 17 May 2002 12:12:55 +0200 | From | Martin Dalecki <> | Subject | Re: [PATCH] 2.5.15 IDE 61 |
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Uz.ytkownik Neil Conway napisa?: > Mike Fedyk wrote: > >>On Wed, May 15, 2002 at 12:55:37PM +0100, Neil Conway wrote: >> >>>You can (and must) safely "touch the cable" in between TCQ commands in >>>the right circumstances. You are therefore touching the cable while the >>>hwgroup is busy, hence my suggestion that the flag we use to prevent >>>touching the cable during DMA should be named something other than busy. >> >>Ahh, but with TCQ the concept of busy changes. The wire (simplified) is >>only busy when the tags are being transfered, otherwise the cable is unused >>unless the cable has been "locked" by one of the devices. > > > Hmm: "locked by one of the devices": do you mean a DMA transfer for > example? These are initiated by the host, but proceed asynchronously, > so I'm not sure I'd describe it as being locked "by the device" as > such. At any rate, the IDE code has to remember that the cable is > asynchronously active until DMA ends... (Or I suppose it could just > check the hwif BMDMA bits for the active state.)
Grep for IDE_DMA busy bits to see it - it does precisely this.
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