Re: [PATCH pci] PCI: don't skip probing entire device if first fn OF node has status = "disabled"

Bjorn Helgaas
2023-05-31T16:56:04Z

On Wed, May 31, 2023 at 02:15:09AM +0300, Vladimir Oltean wrote:
> On Tue, May 30, 2023 at 05:27:24PM -0500, Bjorn Helgaas wrote:
> > Ah, you're right, sorry I missed that. Dispensing with the SERDES
> > details would make this more obvious.
>
> Lesson learned. When I had just gotten out of college, every time I asked
> the coworkers in my company what they're up to, I was amazed by them just
> proceeding to tell me all the nitty gritty details of what they're doing
> and debugging, like I was supposed to understand or care for that matter.
> "Dude, can't you just paint the high level idea without using dorky words?"
> Now I'm one of them...

Haha :) Communication is the hardest part!

> > Seems like something in pci_set_of_node() or a quirk could do whatever
> > you need to do.
>
> Could you help me out with a more detailed hint here? I'm not really
> familiar with the PCI core code. You probably mean to suggest leaving a
> stateful flag somewhere, though I'm not exactly sure where that is, that
> would reach pci_scan_slot() enough to be able to alter its decision.

What bad things happen without this patch? I guess we enumerate
Function 0 but in some cases it's not useful? That in itself wouldn't
be a disaster; there are lots of things we enumerate but don't use.
But in this case, maybe a driver would claim Function 0 but it
wouldn't work as expected?

Bjorn