PCI Power management (was: Re: [PATCH 4/13]: PCI Err: e100 ethernet driver recovery

[Linas Vepstas <linas@austin.ibm.com>]

On Wed, Jun 29, 2005 at 06:58:29PM +0200, Andi Kleen was heard to remark:
> > Yep, OK. Pushig the timer would in fact break if the device was marked
> > perm disabled.
> 
> I think for network drivers you should just write a generic error handler
> (perhaps in net/core/dev.c) that calls the watchdog handler. 
> Then all drivers could be easily converted without much code duplication.

Well, there's no watchdog per-se in "struct net_device" -- are you
suggesting I add one?

It looks like I can almost create generic handlers for net devices; 
looks like calling netdev->stop() is enough to handle the error
detection. 

However, a generic bringup would need to call pci_enable_device(), 
and net/core/dev.c does not include pci.h so I can't really do it 
there.  Other than that, a generic recovry routine looks like it might
be possible; I'll have to experiment; its hard to tell by reading code.

This might be the wrong paradigm, though.  The pci error recovery 
routines are *almost identical* to the power-management suspend/resume
routines.  From what I can tell, the only real difference is that 
I want to not actually turn off/on the power. 

Thus, the right thing to do might be to split up the 
struct pci_dev->suspend() and pci_dev->resume() calls into

   suspend()
   poweroff()
   poweron()
   resume()

and then have the generic pci error recovery routines call
suspend/resume only, skipping the poweroff-on calls.  Does that 
sound good?

I'm not sure I can pull this off without having someone from 
the power-management world throw a brick at me.

--linas