Re: pci bridge suspend/resume (Re: PCI not restored correctly after suspend to ram)

[Nate Lawson <nate-Y6VGUYTwhu0@public.gmane.org>]

On Wed, 24 Mar 2004, Russell King wrote:
> The way I discussed with Pat two OLS's ago (I think it was two) was that
> the bus type match method would return a value to indicate how well the
> IDs matched the device.
>
> When a driver matches a device, we remember this value, and call the
> drivers ->probe function, as we do today.
>
> However, when we add a new driver, we attempt to re-match all devices,
> including those with drivers.  If a device with an existing driver is
> found to have a "better" match with the new driver, the original driver's
> ->remove function is called to unbind the driver, and the new driver
> bound to the device.

This can screw up devices that don't allow full shutdown (i.e. require
BIOS initialization).  A two-pass approach works better.  First pass
allows the driver to match an ID but not initialize anything.  Second
allocates resources like memory, IRQs, etc.

> The match function would, for instance, return a lower value for a
> device driver matching only the class IDs, a higher ID for a device
> driver matching only the vendor ID, vendor ID + device ID, and the
> highest value for vendor ID + device ID + class ID.

The driver's match method (first pass) returns a value for how well it
matches the hardware.  The underlying bus code sorts those values and
picks the winning driver to have its initialize routine called.

http://www.freebsd.org/cgi/man.cgi?query=DEVICE_PROBE&sektion=9&apropos=0&manpath=FreeBSD+5.2-RELEASE+and+Ports
http://www.freebsd.org/cgi/man.cgi?query=DEVICE_ATTACH&sektion=9&apropos=0&manpath=FreeBSD+5.2-RELEASE+and+Ports

-Nate


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