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