On Tue, Mar 07, 2023 at 01:57:27PM -0600, Daniel Kaehn wrote:
> On Tue, Mar 7, 2023 at 12:14 PM Andy Shevchenko
> <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > On Tue, Mar 07, 2023 at 02:17:06PM +0100, Benjamin Tissoires wrote:
> > > On Mar 06 2023, Andy Shevchenko wrote:
...
> > > 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.
>
> Just to make sure I'm understanding you correctly:
>
> Are you proposing that specifically this driver directly reads "cell-names"
> from the ACPI DSD to implement this indexing? Or are you proposing a
> kernel-wide mechanism of "overriding" a fwnode name with ACPI?
> (assuming this doesn't exist already, and I'm not just missing it in
> the kernel source)
>
> Or are you proposing something else entirely?
> (apologies if this should be obvious -- throwing up the ACPI newbie
> card again here :) )
Out of the three listed above I'm proposing the first one.
(Maybe it can be called 'reg-names', but it depends on the hardware)
Also look into hierarchical _DSD (it is similar to the children
of the device node without being separate devices).
> In any case, would this be something I should post to the email chain
> with DT and ACPI
> folks for opinions before I start to implement it?
May be, the -names approach is already used widely for clock, interrupt, reset,
phy and nvmem. So it's something we know about.
--
With Best Regards,
Andy Shevchenko
