Re: [PATCH v1 0/2] clk: Rework initialization of i2c_device_ids

["Uwe Kleine-König (The Capable Hub)" <u.kleine-koenig@baylibre.com>]

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Hello,

On Fri, May 15, 2026 at 05:10:38PM +0200, Uwe Kleine-König (The Capable Hub) wrote:
> this series is a preparation for
> 
> 	diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> 	index 23ff24080dfd..aebd3a5e90af 100644
> 	--- a/include/linux/mod_devicetable.h
> 	+++ b/include/linux/mod_devicetable.h
> 	@@ -477,7 +477,11 @@ struct rpmsg_device_id {
> 	 
> 	 struct i2c_device_id {
> 		char name[I2C_NAME_SIZE];
> 	-	kernel_ulong_t driver_data;	/* Data private to the driver */
> 	+	union {
> 	+		/* Data private to the driver */
> 	+		kernel_ulong_t driver_data;
> 	+		const void *driver_data_ptr;
> 	+	};
> 	 };
> 	 
> 	 /* pci_epf */
> 
> and this requires that .driver_data is assigned via a named initializer
> for static data. This requirement isn't a bad one because named
> initializers are also much better readable than list initializers.
> 
> The union added to struct i2c_device_id enables further cleanups like:
> 
> 	diff --git a/drivers/regulator/ad5398.c b/drivers/regulator/ad5398.c
> 	index 0123ca8157a8..84272ba65d08 100644
> 	--- a/drivers/regulator/ad5398.c
> 	+++ b/drivers/regulator/ad5398.c
> 	@@ -207,8 +207,8 @@ struct ad5398_current_data_format {
> 	 static const struct ad5398_current_data_format df_10_4_120 = {10, 4, 0, 120000};
> 	 
> 	 static const struct i2c_device_id ad5398_id[] = {
> 	-	{ .name = "ad5398", .driver_data = (kernel_ulong_t)&df_10_4_120 },
> 	-	{ .name = "ad5821", .driver_data = (kernel_ulong_t)&df_10_4_120 },
> 	+	{ .name = "ad5398", .driver_data_ptr = &df_10_4_120 },
> 	+	{ .name = "ad5821", .driver_data_ptr = &df_10_4_120 },
> 		{ }
> 	 };
> 	 MODULE_DEVICE_TABLE(i2c, ad5398_id);
> 	@@ -219,8 +219,7 @@ static int ad5398_probe(struct i2c_client *client)
> 		struct regulator_init_data *init_data = dev_get_platdata(&client->dev);
> 		struct regulator_config config = { };
> 		struct ad5398_chip_info *chip;
> 	-	const struct ad5398_current_data_format *df =
> 	-			(struct ad5398_current_data_format *)id->driver_data;
> 	+	const struct ad5398_current_data_format *df = id->driver_data_ptr;
> 	 
> 		chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
> 		if (!chip)
> 
> that are an improvement for readability (again!) and it keeps some
> properties of the pointers (here: being const) without having to pay
> attention for that. (I didn't find a good example in drivers/clk, so an
> regulator driver was used to demonstrate the gain.)

I wonder if you still have this series on your radar, it would be great
to get it into 7.2-rc1.

Best regards
Uwe

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