Messages in this thread | | | Date | Tue, 30 Nov 2021 22:59:19 +0200 | From | Andy Shevchenko <> | Subject | Re: [PATCH v11 2/6] gpiolib: allow to specify the firmware node in struct gpio_chip |
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On Tue, Nov 30, 2021 at 09:25:35PM +0100, Bartosz Golaszewski wrote: > On Tue, Nov 30, 2021 at 5:15 PM Andy Shevchenko > <andriy.shevchenko@linux.intel.com> wrote: > > > > On Tue, Nov 30, 2021 at 04:41:23PM +0100, Bartosz Golaszewski wrote: > > > Software nodes allow us to represent hierarchies for device components > > > that don't have their struct device representation yet - for instance: > > > banks of GPIOs under a common GPIO expander. The core gpiolib core > > > > core .. core ?! > > > > > however doesn't offer any way of passing this information from the > > > drivers. > > > > > > This extends struct gpio_chip with a pointer to fwnode that can be set > > > by the driver and used to pass device properties for child nodes. > > > > > > This is similar to how we handle device-tree sub-nodes with > > > CONFIG_OF_GPIO enabled. > > > > Not sure I understand the proposal. Can you provide couple of (simplest) > > examples? > > > > And also it sounds like reinventing a wheel. What problem do you have that you > > need to solve this way? > > > > ... > > > > > +#if IS_ENABLED(CONFIG_OF_GPIO) > > > + if (gc->of_node && gc->fwnode) { > > > + pr_err("%s: tried to set both the of_node and fwnode in gpio_chip\n", > > > + __func__); > > > + return -EINVAL; > > > + } > > > +#endif /* CONFIG_OF_GPIO */ > > > > I don't like this. It seems like a hack right now. > > > > Is it possible to convert all GPIO controller drivers to provide an fwnode > > rather than doing this? (I believe in most of the drivers we can drop > > completely the of_node assignment). > > > > Yes, it's definitely a good idea but I would be careful with just > dropping the of_node assignments as callbacks may depend on them > later.
GPIO library does it for us among these lines:
struct fwnode_handle *fwnode = gc->parent ? dev_fwnode(gc->parent) : NULL;
of_gpio_dev_init(gc, gdev); <<< HERE! acpi_gpio_dev_init(gc, gdev);
/* * Assign fwnode depending on the result of the previous calls, * if none of them succeed, assign it to the parent's one. */ gdev->dev.fwnode = dev_fwnode(&gdev->dev) ?: fwnode;
> Also it's not just about the gpio_chip of_node assignment - > drivers also use a bunch of OF APIs all around the place. I would > prefer that it be done one by one and every modified driver be tested.
That's why we want to eliminate dev->fwnode explicit dereference as a first step (see dev_fwnode() / device_set_node() APIs).
-- With Best Regards, Andy Shevchenko
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