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Re: 2.4.16-ben0 DVD block i/o breaks mouse, pmu

On Sun, 2 Dec 2001, Benjamin Herrenschmidt wrote:

> The question is why DMA would have been disabled in the first place ?
> The kernel is enabling DMA by default on all devices that support it
> connected to the Apple IDE interface.

Actually, that is a really good question and I do not know the answer to
it :). When I tried to reproduce things by rebooting and letting the iBook
sleep and wake up several times, DMA was always enabled. However, before
that DMA was disabled and I did not adjust anything with hdparm myself. To
give some more information, it is a recent iBook Dual USB and I frequently
let it sleep and wake up. My powerctl-scripts do not touch the
configuration of the CD-ROM drive. The one thing which repeatedly does not
work is persistent mounting, i.e. I have to remount the CD after wakeup.
(The IDE driver works O.K., but I always use ide-scsi.)

I do not know if this is relevant (it is at least also related to DMA) but
maybe someone else does: There is one strange thing about the sound
driver. Very infrequently the iBook would make strange obnoxious noises
after waking up from sleep. Closing the lid, waiting, opening the lid
again helped. Once I also observed that the usage count of the sound
driver module was screwed (up to 3, even though no process was using
sound devices), so it could not be unloaded. (The screwed usage count was
with some earlier kernel, though.)


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