On Tue, 2020-07-14 at 13:45 -0500, Bjorn Helgaas wrote: > > > fail for valid arguments on a valid pci_device* ? > > I really like this idea. > > pci_write_config_*() has one return value, and only 100ish of 2500 > callers check for errors. It's sometimes possible for config > accessors to detect PCI errors and return failure, e.g., device was > removed or didn't respond, but most of them don't, and detecting > these > errors is not really that valuable. > > pci_read_config_*() is much more interesting because it returns two > things, the function return value and the value read from the PCI > device, and it's complicated to check both. .../... I agree. It's a mess at the moment. We have separate mechanism to convey PCI errors (among other things the channel state) which should apply to config space when detection is possible. I think returning all 1's is the right thing to do here and avoids odd duplicate error detection logic which I bet you is never properly tested. > > For b), it might be nice to also change other aspects of the > > interface, e.g. passing a pci_host_bridge pointer plus bus number > > instead of a pci_bus pointer, or having the callback in the > > pci_host_bridge structure. > > I like this idea a lot, too. I think the fact that > pci_bus_read_config_word() requires a pci_bus * complicates things in > a few places. > > I think it's completely separate, as you say, and we should defer it > for now because even part a) is a lot of work. I added it to my list > of possible future projects. Agreed on both points. Cheers, Ben.
