Re: [PATCH 14/14] cxl: Add cxl_check_and_switch_mode() API to switch bi-modal cards

[Ian Munsie <imunsie@au1.ibm.com>]

Excerpts from andrew.donnellan's message of 2016-07-07 11:18:37 +1000:
> > This is to balance the 'get' done in cxl_check_and_switch_mode(), right?
> > A comment wouldn't hurt. I think we're missing the 'put' on the first
> > error path above (!bridge).
> 
> Yep, it's to balance the pci_dev_get() in cxl_check_and_switch_mode() - 
> you're right, a comment to that effect wouldn't hurt.
> 
> You're also right about the error path. Will fix in V2.

We could probably use a dedicated error label for all the error paths
before the pci_dev_put in the main function so we don't need it in every
error path.

> > I was half-expecting to see a new entry in the cxl_pci_tbl pci ID table
> > for the Mellanox entry, but no such thing. By what magic is cxl_probe()
> > called after the switch? Because of the device class?
> 
> It matches against the class, as function 0 of the device after reset 
> comes up as a class 1200 processing accelerator.
> 
> Perhaps we should be a bit more explicit though...

If we explicitly match the Vendor + Device ID we will also match the
networking functions, which we can't do, because before the mode switch
there *IS* a CAPI VSEC in one of the networking functions and our driver
would mistake it as a generic accelerator and try to initialise it. We
could add a comment to this effect to the PCI ID table.

Cheers,
-Ian