Re: Patch to make ymfpci legacy address 16 bits

[Jeff Garzik]

Pavel Roskin wrote:
> 
> Hi, Jeff!
> 
> Thanks for your very (!!!) fast response :-)
> 
> > > http://www.red-bean.com/~proski/linux/ymfpci_pm.diff
> >
> > Why not use pci_driver::{suspend,resume} ?
> 
> I'm just a bit conservative. There are several drivers that don't use this
> mechanism, notably trident and maestro. Do you think it's safe to switch
> all sound drivers to the mechanism you are proposing?
> 
> I'm worried about a comment in maestro.c:
> 
>                 /*
>                  * we'd also like to find out about
>                  * power level changes because some biosen
>                  * do mean things to the maestro when they
>                  * change their power state.
>                  */
> 
> If we switch to pci_driver::{suspend,resume}, will it ever be possible to
> add support for any messages other than PM_SUSPEND and PM_RESUME? Probably
> yes, but only in the PCI driver dispatches them.

Basically the PCI core should implement what PM is necessary, because
eventually struct pci_driver will become a more generic struct driver. 
When that happens, drivers using pci_driver::{suspend,resume} will
automagically work under the new system.  To answer your question, the
PCI[/driver] core should support messages other than PM_{SUSPEND,RESUME}
if they need to be supported.  Right now I mostly see suspend/resume
implemented and nothing else, so that is a very straightforward
conversion to the new PCI API.

Why does maestro.c not use my suggestion?  Because it doesn't use struct
pci_driver.
Why does trident.c not use my suggestion?  Only because noone has
written and tested the patch for it yet :)  It uses struct pci_driver
and should be updated to use ::suspend/resume.

> > In ACPI land the kernel should save and restore the PCI device config
> > space and the PCI bus config space.  It is probably that similar is
> > necessary under APM.
> 
> I have never seen any sound driver doing that. I also know that PCI
> settings are saved by some BIOSes on some hardware.

That's because full PM support is still very much a work in progress :) 
The linux-pm-devel sourceforge list has carried recent discussions, as
has linux-kernel.  Patrick Mochel(sp?) @ Transmeta has posted a
hackers-only patch which incorporates my PCI PM work as well as his own
ACPI work to do suspend and resume.

-- 
Jeff Garzik      | Game called on account of naked chick
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