Re: devres and requesting resources

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

> Only rare PCI devices are shareable among multiple drivers.

Really. Let me see
	AGP & EDAC
	Serial/Parallel combo ports
	MPIIX
	CS5520
	Lots of I2C bus stuff
	VGA v 3D

There are quite a few, and some are already quite fun enough with our pci
struct model.

> sata_* at least intentionally used pci_request_regions() because it is 
> obvious from the hardware spec that multiple regions accessed by 
> multiple drivers is highly unlikely, without the driver being 
> specifically coded to support such sharing.  Such sharing code is far 
> beyond simple resource reservation, to avoid stepping on toes when there 
> is a single MMIO region and set of interrupt clearing registers.
> 
> So reading your email it sounds like there are valid cases for both 
> configurations.
> 
> Its a design choice either way, not a bug either way.

It is a flaw: devres that assumes it should grab all resources is unusable
for some other drivers - it is no longer generic and that makes it far
less useful. I've got no problem with the idea of a devres way to say
"and I want it all, mine mine mine" but that should not be the only
behaviour.

Alan