On Tue, Mar 07, 2023 at 02:17:06PM +0100, Benjamin Tissoires wrote:

On Mar 06 2023, Andy Shevchenko wrote:

quoted

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

...

This almost works. Almost because the I2C device is correctly created,
but I have an issue with the GpioInt call which is not properly set by
the kernel and which returns -EDEFER. /o\ 

You can try to utilize _DEP method, but I dunno if it implemented that way in
the Linux that helps your case.

quoted

quoted

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.

quoted

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.

FWIW while trying to enable this, at some point I named the I2C and the
GPIO entries "I2C0" and "GPI0" (with the number '0', not the letter
'o'), and it was not working as you would expect.

It is commonly accepted in the ACPI world that the names do not carry
meaning AFAICT, and so I think I agree with Andy's initial comment
regarding using indexes, not names to also fetch the I2C and GPIO nodes.
You can probably have a fallback mechanism for when "i2c" is not
present, or simply check if you are in DT or not and use the names only
if we are in DT.

The solution is to provide in the main node the list of cell names, that way
you will always know the indices:

  Device (DEV) {
	  _DSD
		  "cell-names" { "i2c", "gpio" } // index of the name is the
						 // index of the cell

	Device (I2C0) {
	}

	Device (GPI0) {
	}
  }

Problem solved.

Thanks a lot to both of you, this will be tremendously helpful to me.

You're welcome!

[1] https://www.kernel.org/doc/html/latest/admin-guide/acpi/ssdt-overlays.html#loading-acpi-ssdts-from-initrd

-- 
With Best Regards,
Andy Shevchenko