Re: [PATCH] 2.5.15 IDE 61

Martin Dalecki
2002-05-17T11:17:09Z

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.