On Wed, Aug 11, 2021 at 02:37:42PM +0200, Linus Walleij wrote:

On Mon, Jul 26, 2021 at 2:54 PM Andy Shevchenko
[off-list ref] wrote:

quoted

For backward compatibility with some legacy devices introduce
a new (*) property gpio-base to read GPIO base. This will allow
further cleanup of the driver.

*) Note, it's not new for GPIO library since mockup driver is
   using it already.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

(...)

quoted

-               pp->gpio_base   = -1;
+               if (fwnode_property_read_u32(fwnode, "gpio-base", &pp->gpio_base))
+                       pp->gpio_base = -1;

This is problematic because we have repeatedly NACKed this property
to be added to device trees.

I don't know about fwnode policies, but in the device tree this would have
to be "linux,gpio-base" and then it would be NACKed because of adding
an operating-system specific thing to a OS-independent hardware
description.

I don't know what to do with this really, but I understand the need of it
as a kernel-internal thing, however I am afraid that adding this will make
it possible to add linux,gpio-base = <n> to any device tree gpio_chip
as well and that encourages bad behaviour even if we don't allow a
DT binding (YAML) like that.

Is there a way to make a fwnode property only come from software
nodes and not allowed to be used in ACPI or DT? (I guess not...)

This has been the very same concern by Serge and we agreed on limiting this to
software nodes only. And I have seen you are fine with the approach, thanks!

-- 
With Best Regards,
Andy Shevchenko