On Fri, Jan 19, 2024 at 10:34 AM Lukas Wunner [off-list ref] wrote:

On Fri, Jan 19, 2024 at 12:52:00PM +0100, Bartosz Golaszewski wrote:

quoted

We have two separate issues: one is powering-up a PCI device so that
it can be detected

Just wondering, I note in really_probe() we configure the pin controller,
active the pm_domain etc before probing a driver.

Would it make sense for the issue you mention above to similarly
amend pci_scan_device() to enable whatever clocks or regulators
are described in the devicetree as providers for the given PCI device?

If you mean via a callback to some device specific code, then yes, I
think that's exactly what should be done here. That's roughly what
MDIO does. If firmware says there is a device present, then probe it
anyways even if not detected. I don't think that will work for PCI
because it accesses a lot of registers before probe. We'd need some
sort of pre-probe hook instead called after reading vendor and device
ID, but before anything else.

If you mean PCI core just enable whatever clocks and regulators (and
GPIOs), then no, because what is the correct order and timing for each
of those? You don't know because that is device specific information
just as how to program a device is.

Rob