Hi Hans,

Thanks for the review.

The current header-based approach lets i2c-hid-acpi-prp0001.c work
independently by just including a header for the _DSM helper. Switching
to EXPORT_SYMBOL_GPL would force prp0001 to depend on i2c-hid-acpi —
a Kconfig "depends on I2C_HID_ACPI", plus module-level dependency at
load time — all for sharing a single function. I find that hard to
accept.

I understand that adding a new header for one function is unusual,
though it contains only a single static inline and introduces no runtime
dependency between the two drivers.

Looking back at the full discussion: Benjamin made it clear from the
start that he doesn't want i2c-hid-of.c handling ACPI _DSM fallback.
His line is that ACPI devices and OF devices should each go through
their own drivers without cross-contamination. If you still prefer
exporting the function from i2c-hid-acpi.c, then prp0001 would have to
drag i2c-hid-acpi along with it — an independent leaf driver turned
into something that can't stand alone.

If you still prefer the export approach, then I'd rather take a simpler
approach: add an of_match directly to i2c-hid-acpi.c, and return
-ENODEV silently at the top of probe if hid-descr-addr is present. Same
logic as the prp0001 driver, but one fewer file, no module dependency,
no extra Kconfig entry, and no OF driver touching ACPI devices — which
should also satisfy Benjamin's concern.

[corrected: s/prototype/function/ — the header contains a definition,
not just a declaration]

Regards,
Zhibang