Thread (19 messages) 19 messages, 4 authors, 2026-03-25

Re: [PATCH v3 3/7] pinctrl: pinctrl-generic: add __pinctrl_generic_pins_function_dt_node_to_map()

From: Conor Dooley <conor@kernel.org>
Date: 2026-03-25 17:35:03
Also in: imx, linux-devicetree, linux-gpio, lkml
Subsystem: pin control subsystem, the rest · Maintainers: Linus Walleij, Linus Torvalds

On Wed, Mar 25, 2026 at 11:09:20AM -0400, Frank Li wrote:
On Wed, Mar 25, 2026 at 10:33:05AM +0000, Conor Dooley wrote:
quoted
On Tue, Mar 24, 2026 at 04:16:10PM -0400, Frank Li wrote:
quoted
On Fri, Mar 20, 2026 at 09:54:45AM -0400, Frank Li wrote:
quoted
On Fri, Mar 20, 2026 at 02:27:21PM +0100, Linus Walleij wrote:
quoted
On Thu, Mar 19, 2026 at 12:04 AM Frank Li [off-list ref] wrote:
quoted
On Mon, Mar 16, 2026 at 10:37:28AM +0100, Linus Walleij wrote:
quoted
quoted
That said: in this case you're just adding a parameter, just add
the parameter and change all of the in-tree users to pass false
or whatever you need, these is just one (1) in-tree user anyway.
pinctrl_generic_pins_function_dt_node_to_map() directly feed to
.dt_node_to_map() callback, add parameter will impact too much.
Why do you say that. It already has many parameters, one more
or less doesn't matter. It's not like this call is performance-critical.
Just change the users.
In only user drivers/pinctrl/microchip/pinctrl-mpfs-mssio.c,
	.dt_node_to_map = pinctrl_generic_pins_function_dt_node_to_map;

pinctrl_generic_pins_function_dt_node_to_map() need match .dt_node_to_map()'s
declear.

So it can't direct add two parameters in pinctrl_generic_pins_function_dt_node_to_map()
Need simple wrap function, which other in pinctrl-mpfs-mssio.c or in
pinconf.h.

If add two parameter in .dt_node_to_map(), need change all functions, which
.dt_node_to_map = xxx_to_map(). and OF core part.
Linus Walleij:
	Is my explain clear enough? I am preparing respin it?

	is okay use wrap function
	pinctrl_generic_pins_function_dt_node_to_map_ext()?
I don't understand this patch. The function is called
pinctrl_generic_pins_function_dt_node_to_map(). You have no pins.
You're adding a parameter to make a function with *pins* in its name not
use pins. The new function doesn't use pins but has pins in the name.
At the very least function names should not be misleading.

I was going to suggest pulling out the relevant portions and creating
some helpers that could be used by multiple different-but-similar
functions, but I don't actually even think that there's much in common.
Most damningly I think, you don't actually read either the functions or
pins properties at all and neither are permitted by your binding.
So turns out you use neither pins or functions...

You don't actually have any of these properties which runs counter to the
goal of the function, which is parsing. With this in mind, it feels to me
like you're trying way too hard to make use of a generic function when the
right thing to do is probably just have an entirely custom function.
Maybe that's a custom implementation in your driver, or a new function
here, but I think writing that will highlight just how little of the
code would be shared between the existing function and what your
use-case needs: no pin configuration stuff, no reading of the devicetree
other than the node names and no dealing with the label pointing to the
"wrong" place.

I recently bought a spacemit k1 board to go and write a sister function
to pinctrl_generic_pins_function_dt_node_to_map() that deals with pins
and groups (because that's a pretty common pattern).
I would be calling that pinctrl_generic_pinmux_dt_node_to_map(),
because it that's the property it deals with. I have honestly got no
idea what to call one for this situation since you don't have any of the
properties in pinmux-node.yaml. Maybe that's a sign.
At v2, I implemented customize dt_node_to_map(), Linus Walleij think it is
too similar with pinctrl_generic_pins_function_dt_node_to_map(), so ask me
to enhanance and reuse pinctrl_generic_pins_function_dt_node_to_map().
Sure, and he's right that there's a lot similar. Everything you want to
do, other than looking at the mux state, is something that
pinctrl_generic_pins_function_dt_node_to_map() does. But bastardising
a function that's explicitly about reading pins and functions properties
to do things that have _neither_ is not a good implementation of that
review feedback.

If you're going to make something generic, the right level to hook in
IMO is at the pinctrl_generic_pins_function_dt_subnode_to_map() level,
I already know that 95% of the code in that function is identical to
what will be used for the spacemit k1 that uses the pinmux property
and changing its API is a lot easier than changing the API of something
that is written to match the dt_node_to_map callback.
You don't even benefit from the extra functionality that
pinctrl_generic_pins_function_dt_node_to_map() provides, because you
don't have ambiguity about where the phandle you're parsing from points.
In your case, it has to be the group node.

pinctrl_generic_pins_function_dt_subnode_to_map() could probably be
split into two parts, one that does the dt parsing portion and a second
portion that does the mapping to kernel data structures. The first
portion of that is the for loop. The second portion is everything after
the for loop and the bit that names the groups. IOW, do something like
what I am pasting here, and you create your own function that wraps
pinctrl_generic_to_map() in the way you want. I personally think this is
more tasteful than what you've done, and more importantly I am pretty
sure that this is what's needed to be able to maximise code reuse for
the devices that use pinmux. I didn't compile this or anything, it's
just speculative.
diff --git a/drivers/pinctrl/pinctrl-generic.c b/drivers/pinctrl/pinctrl-generic.c
index efb39c6a67033..7f02af6d9f3e4 100644
--- a/drivers/pinctrl/pinctrl-generic.c
+++ b/drivers/pinctrl/pinctrl-generic.c
@@ -17,56 +17,30 @@
 #include "pinctrl-utils.h"
 #include "pinmux.h"
 
-static int pinctrl_generic_pins_function_dt_subnode_to_map(struct pinctrl_dev *pctldev,
-							   struct device_node *parent,
-							   struct device_node *np,
-							   struct pinctrl_map **maps,
-							   unsigned int *num_maps,
-							   unsigned int *num_reserved_maps,
-							   const char **group_names,
-							   unsigned int ngroups)
+static int pinctrl_generic_to_map(struct pinctrl_dev *pctldev,
+				  struct device_node *parent,
+				  struct device_node *np,
+				  struct pinctrl_map **maps,
+				  unsigned int *num_maps,
+				  unsigned int *num_reserved_maps,
+				  const char **group_names,
+				  unsigned int ngroups,
+				  const char **functions,
+				  unsigned int *pins,
+				  void *function_data)
 {
 	struct device *dev = pctldev->dev;
-	const char **functions;
 	const char *group_name;
 	unsigned long *configs;
-	unsigned int num_configs, pin, *pins;
+	unsigned int num_configs;
 	int npins, ret, reserve = 1;
 
-	npins = of_property_count_u32_elems(np, "pins");
-
-	if (npins < 1) {
-		dev_err(dev, "invalid pinctrl group %pOFn.%pOFn %d\n",
-			parent, np, npins);
-		return npins;
-	}
-
 	group_name = devm_kasprintf(dev, GFP_KERNEL, "%pOFn.%pOFn", parent, np);
 	if (!group_name)
 		return -ENOMEM;
 
 	group_names[ngroups] = group_name;
 
-	pins = devm_kcalloc(dev, npins, sizeof(*pins), GFP_KERNEL);
-	if (!pins)
-		return -ENOMEM;
-
-	functions = devm_kcalloc(dev, npins, sizeof(*functions), GFP_KERNEL);
-	if (!functions)
-		return -ENOMEM;
-
-	for (int i = 0; i < npins; i++) {
-		ret = of_property_read_u32_index(np, "pins", i, &pin);
-		if (ret)
-			return ret;
-
-		pins[i] = pin;
-
-		ret = of_property_read_string(np, "function", &functions[i]);
-		if (ret)
-			return ret;
-	}
-
 	ret = pinctrl_utils_reserve_map(pctldev, maps, num_reserved_maps, num_maps, reserve);
 	if (ret)
 		return ret;
@@ -101,6 +75,52 @@ static int pinctrl_generic_pins_function_dt_subnode_to_map(struct pinctrl_dev *p
 		return ret;
 
 	return 0;
+}
+
+static int pinctrl_generic_pins_function_dt_subnode_to_map(struct pinctrl_dev *pctldev,
+							   struct device_node *parent,
+							   struct device_node *np,
+							   struct pinctrl_map **maps,
+							   unsigned int *num_maps,
+							   unsigned int *num_reserved_maps,
+							   const char **group_names,
+							   unsigned int ngroups)
+{
+	struct device *dev = pctldev->dev;
+	const char **functions;
+	unsigned int pin, *pins;
+	int npins, ret;
+
+	npins = of_property_count_u32_elems(np, "pins");
+
+	if (npins < 1) {
+		dev_err(dev, "invalid pinctrl group %pOFn.%pOFn %d\n",
+			parent, np, npins);
+		return npins;
+	}
+
+	pins = devm_kcalloc(dev, npins, sizeof(*pins), GFP_KERNEL);
+	if (!pins)
+		return -ENOMEM;
+
+	functions = devm_kcalloc(dev, npins, sizeof(*functions), GFP_KERNEL);
+	if (!functions)
+		return -ENOMEM;
+
+	for (int i = 0; i < npins; i++) {
+		ret = of_property_read_u32_index(np, "pins", i, &pin);
+		if (ret)
+			return ret;
+
+		pins[i] = pin;
+
+		ret = of_property_read_string(np, "function", &functions[i]);
+		if (ret)
+			return ret;
+	}
+	return pinctrl_generic_to_map(pctldev, parent, np, maps, num_maps,
+				  num_reserved_maps, group_names, ngroups,
+				  functions, pins, NULL);
 };
 
 /*

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