Re: Saving device driver state during shutdown

David Woodhouse (David.Woodhouse@mvhi.com)
Wed, 04 Aug 1999 09:03:52 +0100

joec@ensoniq.com said:
> This was the solution I was thinking about. It seems to me that the
> drivers should be responsible for saving the hardware persistance.
> Forgetting the mixer state for a second, saving off hardware register
> state is a requirement for some power managment schemes.

I'm not too bothered who's "responsible" for it - as long as it's actually
possible to do it. I'm happy to handle it in user-space as much as possible,
but we need a small amount of modification to the kernel drivers to make that
possible - that is; a way of passing the required mixer levels to the driver
when it starts up (or postponing the mixer init until it's given the levels by
an ioctl), and a way of obtaining the final settings from the driver before
it's unloaded.

> This brings up another point. I want to save state as a means of
> getting away from passing command line parameters. This is a scary
> prospect for the new Linux user.

I meant this to be automated - the levels recorded from the previous
incarnation of the driver should be passed to the new incarnation without the
user ever seeing them.

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David Woodhouse David.Woodhouse@mvhi.com Office: (+44) 1223 810302
Project Leader, Process Information Systems Mobile: (+44) 976 658355
Axiom (Cambridge) Ltd., Swaffham Bulbeck, Cambridge, CB5 0NA, UK.
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