On Thu, Dec 02, 2021 at 12:24:06PM +0100, Bartosz Golaszewski wrote:

On Thu, Dec 2, 2021 at 11:58 AM Andy Shevchenko
[off-list ref] wrote:

quoted

On Wed, Dec 01, 2021 at 02:11:28PM +0100, Bartosz Golaszewski wrote:

quoted

On Tue, Nov 30, 2021 at 10:04 PM Bartosz Golaszewski [off-list ref] wrote:

...

quoted

Let me maybe rephrase the problem: currently, for GPIO devices
instantiating multiple banks created outside of the OF or ACPI
frameworks (e.g. instantiated manually and configured using a
hierarchy of software nodes with a single parent swnode and a number
of child swnodes representing the children), it is impossible to
assign firmware nodes other than the one representing the top GPIO
device to the gpiochip child devices.

In fact if we want to drop the OF APIs entirely from gpiolib - this
would be the right first step as for gpio-sim it actually replaces the
gc->of_node = some_of_node; assignment that OF-based drivers do for
sub-nodes defining banks and it does work with device-tree (I verified
that too) thanks to the fwnode abstraction layer.

In exchange of acknowledgements I confirm that I understood the issue
you are describing. What I still don't like is this band-aid:ish approach.
What we really need is to replace of_node by fwnode in GPIO library once
for all. But it can be done later after your simulation series (or before,
i.o.w. independently), hence I propose to update TODO and do it separately.

But this is what we already do for OF. How would the core gpiolib know
how the firmware nodes represent the banks? It's the driver's job to
tell the framework which node corresponds with what. If anything, we
should start replacing of_nodes with fwnodes in drivers and eventually
we'd drop the of_node pointer from gpio_chip entirely, but we'd keep
the fwnode pointer I added as the driver still needs to assign it
itself.

Again: I may be missing something here but I've been going through
this on and on and can't figure out any other way. Looking at
gpiolib-acpi.c I don't see it correctly assigning fwnodes to
sub-devices either but I don't have any HW to test it.

As for this series: I can't really drop this patch as gpio-sim relies
on swnodes being correctly associated with gpio_chips to identify the
gpiodevs from configfs callbacks.

Then we need to replace of_node by fwnode as a first step. I have looked
briefly into the list of drivers that may have been cleaned up and it doesn't
look too long.

-- 
With Best Regards,
Andy Shevchenko