Re: [PATCH v8 3/3] HID: cp2112: Fwnode Support

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Mon, Mar 06, 2023 at 01:40:16PM -0600, Daniel Kaehn wrote:

...

> Device (SE9)
> {
>     Name (_ADR, 0x001D0001) // _ADR: Address
>     Device (RHUB)
>     {
>         Name (_ADR, Zero)
>         Device (CP2) // the USB-hid & CP2112 shared node
>         {
>             Name (_ADR, One)
>         }
>     }
> }
> 
> If I'm understanding correctly, this adds the SE9 device as function 1
> of PCI device 0x1d,

To be precise this does not add the device. It adds a description of
the companion device in case the real one will appear on the PCI bus
with BDF 00:1d.1.

> then RHUB as the USB controller it provides, and finally, CP2 as the
> USB device attached to port 1 of the controller.
> 
> With this as the loaded dsdt table, the USB device now has a firmware_node :)
> #> cat /sys/bus/usb/devices/3-1:1.0/firmware_node/path
> \_SB_.PCI0.SE9_.RHUB.CP2_
> 
> After applying my patches, the HID device also references this node:
> #> cat /sys/bus/hid/devices/0003:10C4:EA90.0003/firmware_node/path
> \_SB_.PCI0.SE9_.RHUB.CP2_
> 
> With this all said -- I noticed iasl prints this statement when trying
> to create a node with a lowercase name:
> "At least one lower case letter found in NameSeg, ASL is case
> insensitive - converting to upper case (GPIO)"

Yes, because it should be in the upper case.

> I wonder if this suggests that adding a call to toupper() to
> acpi_fwnode_get_named_child_node would be
> an appropriate solution for the node name casing issue....

I dunno. You need to ask in the linux-acpi@ mailing list.
To me this is corner case that can't be easily solved
(because two different specifications treat it differently.

You also need to ask DT people about capital letters there.
And my guts tell me that it's probably also carved in the spec
as "must be lower case" or alike.

-- 
With Best Regards,
Andy Shevchenko