media: Add a helper for obtaining the clock producer

Introduce a helper for v4l2 sensor drivers on both DT- and ACPI-based platforms to retrieve a reference to the clock producer from firmware.

This helper behaves the same as clk_get_optional() except where there is

no clock producer like in ACPI-based platforms.

For ACPI-based platforms the function will read the "clock-frequency" ACPI _DSD property and register a fixed frequency clock with the frequency indicated in the property.

This function also handles the special ACPI-based system case where:
The clock-frequency _DSD property is present.
A reference to the clock producer is present, where the clock is provided by a camera sensor PMIC driver (e.g. int3472/tps68470.c)
In this case try to set the clock-frequency value to the provided clock.

Signed-off-by Mehdi Djait <[email protected]>

drivers/media/v4l2-core/v4l2-common.c +49 -0

index bd160a8c9efe..c53221165c5a 100644
@@ -34,6 +34,9 @@
  * Added Gerd Knorrs v4l1 enhancements (Justin Schoeman)
  */
 
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/kernel.h>

@@ -673,3 +676,49 @@ int v4l2_link_freq_to_bitmap(struct device *dev, const u64 *fw_link_freqs,
 	return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_link_freq_to_bitmap);
+
+struct clk *devm_v4l2_sensor_clk_get(struct device *dev, const char *id)
+{
+	const char *clk_id __free(kfree) = NULL;
+	struct clk_hw *clk_hw;
+	struct clk *clk;
+	bool acpi_node;
+	u32 rate;
+	int ret;
+
+	clk = devm_clk_get_optional(dev, id);
+	ret = device_property_read_u32(dev, "clock-frequency", &rate);
+	acpi_node = is_acpi_node(dev_fwnode(dev));
+
+	if (clk) {
+		if (!ret && acpi_node) {
+			ret = clk_set_rate(clk, rate);
+			if (ret) {
+				dev_err(dev, "Failed to set clock rate: %u\n",
+					rate);
+				return ERR_PTR(ret);
+			}
+		}
+		return clk;
+	}
+
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (!IS_ENABLED(CONFIG_COMMON_CLK) || !acpi_node)
+		return ERR_PTR(-ENOENT);
+
+	if (!id) {
+		clk_id = kasprintf(GFP_KERNEL, "clk-%s", dev_name(dev));
+		if (!clk_id)
+			return ERR_PTR(-ENOMEM);
+		id = clk_id;
+	}
+
+	clk_hw = devm_clk_hw_register_fixed_rate(dev, id, NULL, 0, rate);
+	if (IS_ERR(clk_hw))
+		return ERR_CAST(clk_hw);
+
+	return clk_hw->clk;
+}
+EXPORT_SYMBOL_GPL(devm_v4l2_sensor_clk_get);

include/media/v4l2-common.h +0 -0

index 0a43f56578bc..72d8fcc6057f 100644
@@ -620,6 +620,31 @@ int v4l2_link_freq_to_bitmap(struct device *dev, const u64 *fw_link_freqs,
 			     unsigned int num_of_driver_link_freqs,

include/media/v4l2-common.h +0 -0

 static inline u64 v4l2_buffer_get_timestamp(const struct v4l2_buffer *buf)
 {
 	/*

Add the new v4l2 helper devm_v4l2_sensor_clk_get() to Documentation. the helper works on both DT- and ACPI-based platforms to retrieve a reference to the clock producer from firmware.

Signed-off-by Mehdi Djait <[email protected]>

Documentation/driver-api/media/camera-sensor.rst +0 -0

index c290833165e6..c82c018a5f40 100644

Documentation/driver-api/media/camera-sensor.rst +0 -0

 Devicetree

Hi Mehdi,

Thank you for the patch.

Quoted 11 lines · Mehdi Djait

Add the new v4l2 helper devm_v4l2_sensor_clk_get() to Documentation. the helper works on both DT- and ACPI-based platforms to retrieve a reference to the clock producer from firmware.

Signed-off-by Mehdi Djait <[email protected]>

Documentation/driver-api/media/camera-sensor.rst +0 -0

index c290833165e6..c82c018a5f40 100644

Documentation/driver-api/media/camera-sensor.rst user. · line 37

Quoted 7 lines

Documentation/driver-api/media/camera-sensor.rst +2 -1

@@ -32,7 +32,8 @@ user.
 ACPI
 ~~~~
 
-Read the ``clock-frequency`` _DSD property to denote the frequency. The driver
+Use ``devm_v4l2_sensor_clk_get()`` to get the clock. The function will read the
+``clock-frequency`` _DSD property to denote the frequency. The driver
 can rely on this frequency being used.

This isn't specific to ACPI anymore. I think the documentation should be refactored further. Here's a proposal.

Handling clocks
---------------

Camera sensors have an internal clock tree including a PLL and a number of divisors. The clock tree is generally configured by the driver based on a few input parameters that are specific to the hardware: the external clock frequency and the link frequency. The two parameters generally are specified by system firmware. **No other frequencies should be used in any circumstances.**

The reason why the clock frequencies are so important is that the system is usually designed to use specific external clock and link frequencies to ensure electro-magnetic compatibility. Using other frequencies may cause harmful effects elsewhere. Therefore only the pre-determined frequencies are configurable by the user.

The external clock frequency shall be retrieved by obtaining the external clock using the ``devm_v4l2_sensor_clk_get()`` helper function, and then getting its frequency with ``clk_get_rate()``. Usage of the helper function guarantees correct behaviour regardless of whether the sensor is integrated in a DT-based or ACPI-based system.

ACPI
~~~~

ACPI-based systems typically don't register the sensor external clock with the kernel, but specify the external clock frequency in the ``clock-frequency`` _DSD property. The ``devm_v4l2_sensor_clk_get()`` helper creates and returns a fixed clock set at that rate.

Devicetree
~~~~~~~~~~

Devicetree-based systems declare the sensor external clock in the device tree and reference it from the sensor node. The preferred way to select the external clock frequency is to use the ``assigned-clocks``, ``assigned-clock-parents`` and ``assigned-clock-rates`` properties in the sensor node to set the clock rate. See the `clock device tree bindings
<https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/clock/clock.yaml>`_
for more information. The ``devm_v4l2_sensor_clk_get()`` helper retrieves and returns that clock.

This approach has the drawback that there's no guarantee that the frequency hasn't been modified directly or indirectly by another driver, or supported by the board's clock tree to begin with. Changes to the Common Clock Framework API are required to ensure reliability.

Quoted 4 lines

Documentation/driver-api/media/camera-sensor.rst +0 -0

 Devicetree

devm_clk_get() fails on ACPI-based platforms, where firmware does not provide a direct reference to the clock producer.

Replace devm_clk_get() with the new v4l2 helper devm_v4l2_sensor_clk_get() that works on both DT- and ACPI-based platforms to retrieve a reference to the clock producer from firmware.

Signed-off-by Mehdi Djait <[email protected]>

devm_clk_get() fails on ACPI-based platforms, where firmware does not provide a direct reference to the clock producer.

Replace devm_clk_get() with the new v4l2 helper devm_v4l2_sensor_clk_get() that works on both DT- and ACPI-based platforms to retrieve a reference to the clock producer from firmware.

Signed-off-by Mehdi Djait <[email protected]>

drivers/media/i2c/imx415.c +0 -0

index 9f37779bd611..f7897660f44f 100644

devm_clk_get() fails on ACPI-based platforms, where firmware does not provide a direct reference to the clock producer.

Replace devm_clk_get() with the new v4l2 helper devm_v4l2_sensor_clk_get() that works on both DT- and ACPI-based platforms to retrieve a reference to the clock producer from firmware.

Signed-off-by Mehdi Djait <[email protected]>

drivers/media/i2c/ov8865.c +3 -29

index 95ffe7536aa6..5cc278c3e169 100644
@@ -2956,7 +2956,6 @@ static int ov8865_probe(struct i2c_client *client)
 	struct ov8865_sensor *sensor;
 	struct v4l2_subdev *subdev;
 	struct media_pad *pad;
-	unsigned int rate = 0;
 	unsigned int i;
 	int ret;
 

@@ -3019,39 +3018,14 @@ static int ov8865_probe(struct i2c_client *client)
 
 	/* External Clock */
 
-	sensor->extclk = devm_clk_get(dev, NULL);
-	if (PTR_ERR(sensor->extclk) == -ENOENT) {
-		dev_info(dev, "no external clock found, continuing...\n");
-		sensor->extclk = NULL;
-	} else if (IS_ERR(sensor->extclk)) {
+	sensor->extclk = devm_v4l2_sensor_clk_get(dev, NULL);
+	if (IS_ERR(sensor->extclk)) {
 		dev_err(dev, "failed to get external clock\n");
 		ret = PTR_ERR(sensor->extclk);
 		goto error_endpoint;
 	}
 
-	/*
-	 * We could have either a 24MHz or 19.2MHz clock rate from either dt or
-	 * ACPI...but we also need to support the weird IPU3 case which will
-	 * have an external clock AND a clock-frequency property. Check for the
-	 * clock-frequency property and if found, set that rate if we managed
-	 * to acquire a clock. This should cover the ACPI case. If the system
-	 * uses devicetree then the configured rate should already be set, so
-	 * we can just read it.
-	 */
-	ret = fwnode_property_read_u32(dev_fwnode(dev), "clock-frequency",
-				       &rate);
-	if (!ret && sensor->extclk) {
-		ret = clk_set_rate(sensor->extclk, rate);
-		if (ret) {
-			dev_err_probe(dev, ret, "failed to set clock rate\n");
-			goto error_endpoint;
-		}
-	} else if (ret && !sensor->extclk) {
-		dev_err_probe(dev, ret, "invalid clock config\n");
-		goto error_endpoint;
-	}
-
-	sensor->extclk_rate = rate ? rate : clk_get_rate(sensor->extclk);
+	sensor->extclk_rate = clk_get_rate(sensor->extclk);
 
 	for (i = 0; i < ARRAY_SIZE(supported_extclk_rates); i++) {
 		if (sensor->extclk_rate == supported_extclk_rates[i])

Hi Mehdi,

Thank you for the patch.

Quoted 8 lines · Mehdi Djait

devm_clk_get() fails on ACPI-based platforms, where firmware does not provide a direct reference to the clock producer.

Replace devm_clk_get() with the new v4l2 helper devm_v4l2_sensor_clk_get() that works on both DT- and ACPI-based platforms to retrieve a reference to the clock producer from firmware.

Signed-off-by Mehdi Djait <[email protected]>

Reviewed-by Laurent Pinchart <[email protected]>

Quoted 17 lines

drivers/media/i2c/ov8865.c +0 -1

index 95ffe7536aa6..5cc278c3e169 100644
@@ -2956,7 +2956,6 @@ static int ov8865_probe(struct i2c_client *client)
 	struct ov8865_sensor *sensor;
 	struct v4l2_subdev *subdev;
 	struct media_pad *pad;
-	unsigned int rate = 0;
 	unsigned int i;
 	int ret;
 

@@ -3019,39 +3018,14 @@ static int ov8865_probe(struct i2c_client *client)
 
 	/* External Clock */
 

drivers/media/i2c/ov8865.c static int ov8865_probe(struct i2c_client *client) · line 3024

Quoted 9 lines

drivers/media/i2c/ov8865.c +2 -5

-	sensor->extclk = devm_clk_get(dev, NULL);
-	if (PTR_ERR(sensor->extclk) == -ENOENT) {
-		dev_info(dev, "no external clock found, continuing...\n");
-		sensor->extclk = NULL;
-	} else if (IS_ERR(sensor->extclk)) {
+	sensor->extclk = devm_v4l2_sensor_clk_get(dev, NULL);
+	if (IS_ERR(sensor->extclk)) {
 		dev_err(dev, "failed to get external clock\n");
 		ret = PTR_ERR(sensor->extclk);

Quoted 30 lines

drivers/media/i2c/ov8865.c +1 -23

 		goto error_endpoint;
 	}
 
-	/*
-	 * We could have either a 24MHz or 19.2MHz clock rate from either dt or
-	 * ACPI...but we also need to support the weird IPU3 case which will
-	 * have an external clock AND a clock-frequency property. Check for the
-	 * clock-frequency property and if found, set that rate if we managed
-	 * to acquire a clock. This should cover the ACPI case. If the system
-	 * uses devicetree then the configured rate should already be set, so
-	 * we can just read it.
-	 */
-	ret = fwnode_property_read_u32(dev_fwnode(dev), "clock-frequency",
-				       &rate);
-	if (!ret && sensor->extclk) {
-		ret = clk_set_rate(sensor->extclk, rate);
-		if (ret) {
-			dev_err_probe(dev, ret, "failed to set clock rate\n");
-			goto error_endpoint;
-		}
-	} else if (ret && !sensor->extclk) {
-		dev_err_probe(dev, ret, "invalid clock config\n");
-		goto error_endpoint;
-	}
-
-	sensor->extclk_rate = rate ? rate : clk_get_rate(sensor->extclk);
+	sensor->extclk_rate = clk_get_rate(sensor->extclk);
 
 	for (i = 0; i < ARRAY_SIZE(supported_extclk_rates); i++) {
 		if (sensor->extclk_rate == supported_extclk_rates[i])

Quoted 33 lines · Laurent Pinchart

Hi Mehdi,

Thank you for the patch.

Quoted 8 lines · Mehdi Djait

devm_clk_get() fails on ACPI-based platforms, where firmware does not provide a direct reference to the clock producer.

Replace devm_clk_get() with the new v4l2 helper devm_v4l2_sensor_clk_get() that works on both DT- and ACPI-based platforms to retrieve a reference to the clock producer from firmware.

Signed-off-by Mehdi Djait <[email protected]>

Reviewed-by Laurent Pinchart <[email protected]>

Quoted 17 lines

drivers/media/i2c/ov8865.c +0 -1

index 95ffe7536aa6..5cc278c3e169 100644
@@ -2956,7 +2956,6 @@ static int ov8865_probe(struct i2c_client *client)
 	struct ov8865_sensor *sensor;
 	struct v4l2_subdev *subdev;
 	struct media_pad *pad;
-	unsigned int rate = 0;
 	unsigned int i;
 	int ret;
 

@@ -3019,39 +3018,14 @@ static int ov8865_probe(struct i2c_client *client)
 
 	/* External Clock */
 

Quoted 9 lines

drivers/media/i2c/ov8865.c static int ov8865_probe(struct i2c_client *client) · line 3024

Quoted 9 lines

drivers/media/i2c/ov8865.c +2 -5

-	sensor->extclk = devm_clk_get(dev, NULL);
-	if (PTR_ERR(sensor->extclk) == -ENOENT) {
-		dev_info(dev, "no external clock found, continuing...\n");
-		sensor->extclk = NULL;
-	} else if (IS_ERR(sensor->extclk)) {
+	sensor->extclk = devm_v4l2_sensor_clk_get(dev, NULL);
+	if (IS_ERR(sensor->extclk)) {
 		dev_err(dev, "failed to get external clock\n");
 		ret = PTR_ERR(sensor->extclk);

Actually, I'd take this as an opportunity to write

ret = dev_err_probe(dev, PTR_ERR(sensor->extclk),

				    "failed to get external clock\n");

Hi Laurent,

Quoted 46 lines · Laurent Pinchart

Quoted 33 lines · Laurent Pinchart

Hi Mehdi,

Thank you for the patch.

Quoted 8 lines · Mehdi Djait

devm_clk_get() fails on ACPI-based platforms, where firmware does not provide a direct reference to the clock producer.

Replace devm_clk_get() with the new v4l2 helper devm_v4l2_sensor_clk_get() that works on both DT- and ACPI-based platforms to retrieve a reference to the clock producer from firmware.

Signed-off-by Mehdi Djait <[email protected]>

Reviewed-by Laurent Pinchart <[email protected]>

Quoted 17 lines

drivers/media/i2c/ov8865.c +0 -1

index 95ffe7536aa6..5cc278c3e169 100644
@@ -2956,7 +2956,6 @@ static int ov8865_probe(struct i2c_client *client)
 	struct ov8865_sensor *sensor;
 	struct v4l2_subdev *subdev;
 	struct media_pad *pad;
-	unsigned int rate = 0;
 	unsigned int i;
 	int ret;
 

@@ -3019,39 +3018,14 @@ static int ov8865_probe(struct i2c_client *client)
 
 	/* External Clock */
 

Quoted 9 lines

drivers/media/i2c/ov8865.c static int ov8865_probe(struct i2c_client *client) · line 3024

Quoted 9 lines

drivers/media/i2c/ov8865.c +2 -5

-	sensor->extclk = devm_clk_get(dev, NULL);
-	if (PTR_ERR(sensor->extclk) == -ENOENT) {
-		dev_info(dev, "no external clock found, continuing...\n");
-		sensor->extclk = NULL;
-	} else if (IS_ERR(sensor->extclk)) {
+	sensor->extclk = devm_v4l2_sensor_clk_get(dev, NULL);
+	if (IS_ERR(sensor->extclk)) {
 		dev_err(dev, "failed to get external clock\n");
 		ret = PTR_ERR(sensor->extclk);

Actually, I'd take this as an opportunity to write

Quoted 2 lines

ret = dev_err_probe(dev, PTR_ERR(sensor->extclk),

				    "failed to get external clock\n");

Wouldn't printing this kind of a message fit for devm_v4l2_sensor_clk_get() and consequently be removed from drivers?

Use the new v4l2 helper devm_v4l2_sensor_clk_get() that works on both DT- and ACPI-based platforms to retrieve a reference to the clock producer from firmware.

Signed-off-by Mehdi Djait <[email protected]>

drivers/media/i2c/ov2680.c +0 -8

index 7237fb27ecd0..c974169c92f8 100644
@@ -1079,7 +1079,6 @@ static int ov2680_parse_dt(struct ov2680_dev *sensor)
 	struct device *dev = sensor->dev;
 	struct fwnode_handle *ep_fwnode;
 	struct gpio_desc *gpio;
-	unsigned int rate = 0;
 	int i, ret;
 
 	/*

@@ -1114,13 +1113,6 @@ static int ov2680_parse_dt(struct ov2680_dev *sensor)
 
 	sensor->pwdn_gpio = gpio;
 
-	sensor->xvclk = devm_clk_get_optional(dev, "xvclk");
-	if (IS_ERR(sensor->xvclk)) {
-		ret = dev_err_probe(dev, PTR_ERR(sensor->xvclk),
-				    "xvclk clock missing or invalid\n");
-		goto out_free_bus_cfg;
-	}
-
 	/*
 	 * We could have either a 24MHz or 19.2MHz clock rate from either DT or
 	 * ACPI... but we also need to support the weird IPU3 case which will

drivers/media/i2c/ov2680.c +6 -13

-	ret = fwnode_property_read_u32(dev_fwnode(dev), "clock-frequency",
-				       &rate);
-	if (ret && !sensor->xvclk) {
-		dev_err_probe(dev, ret, "invalid clock config\n");
+
+	sensor->xvclk = devm_v4l2_sensor_clk_get(dev, "xvclk");
+	if (IS_ERR(sensor->xvclk)) {
+		ret = dev_err_probe(dev, PTR_ERR(sensor->xvclk),
+				    "xvclk clock missing or invalid\n");
 		goto out_free_bus_cfg;
 	}
 
-	if (!ret && sensor->xvclk) {
-		ret = clk_set_rate(sensor->xvclk, rate);
-		if (ret) {
-			dev_err_probe(dev, ret, "failed to set clock rate\n");
-			goto out_free_bus_cfg;
-		}
-	}
-
-	sensor->xvclk_freq = rate ?: clk_get_rate(sensor->xvclk);
+	sensor->xvclk_freq = clk_get_rate(sensor->xvclk);
 
 	for (i = 0; i < ARRAY_SIZE(ov2680_xvclk_freqs); i++) {
 		if (sensor->xvclk_freq == ov2680_xvclk_freqs[i])

Hello everyone,

Here is my v1 for the new helper v4l2_devm_sensor_clk_get()

Any testing of the patches is GREATLY APPRECIATED! Especially the two drivers with the special ACPI case:
1) OV8865
2) OV2680

Background
----------

A reference to the clock producer is not available to the kernel in ACPI-based platforms but the sensor drivers still need them.

devm_clk_get() will return an error and the probe function will fail.

Solution
--------

Introduce a generic helper for v4l2 sensor drivers on both DT- and ACPI-based platforms.

This helper behaves the same as clk_get_optional() except where there is no clock producer like in ACPI-based platforms.

For ACPI-based platforms the function will read the "clock-frequency" ACPI _DSD property and register a fixed frequency clock with the frequency indicated in the property.

Solution for special ACPI case
------------------------------

This function also handles the special ACPI-based system case where:

1) The clock-frequency _DSD property is present.
2) A reference to the clock producer is present, where the clock is provided by a camera sensor PMIC driver (e.g. int3472/tps68470.c)

In this case try to set the clock-frequency value to the provided clock.

RFC History
-----------

RFC v4 -> RFC v5:
Suggested by Arnd Bergmann:
- removed IS_REACHABLE(CONFIG_COMMON_CLK). IS_REACHABLE() is actually
discouraged [1]. COFIG_COMMON_CLK is a bool, so IS_ENABLED() will be the
right solution here
Suggested by Hans de Goede:
- added handling for the special ACPI-based system case, where
both a reference to the clock-provider and the _DSD
clock-frequency are present.
- updated the function's kernel-doc and the commit msg
to mention this special case.
Link RFC v4: https://lore.kernel.org/linux-media/[email protected]/
[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/Documentation/kbuild/kconfig-language.rst?h=next-20250513&id=700bd25bd4f47a0f4e02e0a25dde05f1a6b16eea

RFC v3 -> RFC v4:
Suggested by Laurent:
- removed the #ifdef to use IS_REACHABLE(CONFIG_COMMON_CLK)
- changed to kasprintf() to allocate the clk name when id is NULL and used the __free(kfree) scope-based cleanup helper when
defining the variable to hold the allocated name
Link v3: https://lore.kernel.org/linux-media/[email protected]/

RFC v2 -> RFC v3:
- Added #ifdef CONFIG_COMMON_CLK for the ACPI case
Link v2: https://lore.kernel.org/linux-media/[email protected]/

RFC v1 -> RFC v2:
Suggested by Sakari:
- removed clk_name
- removed the IS_ERR() check
- improved the kernel-doc comment and commit msg
Link v1: https://lore.kernel.org/linux-media/[email protected]

Mehdi Djait (55):
media: v4l2-common: Add a helper for obtaining the clock producer
Documentation: media: camera-sensor: Mention
v4l2_devm_sensor_clk_get() for obtaining the clock
media: i2c: ar0521: Use the v4l2 helper for obtaining the clock
media: i2c: ds90ub913: Use the v4l2 helper for obtaining the clock
media: i2c: ds90ub960: Use the v4l2 helper for obtaining the clock

media: i2c: et8ek8: Use the v4l2 helper for obtaining the clock
media: i2c: gc05a2: Use the v4l2 helper for obtaining the clock
media: i2c: gc08a3: Use the v4l2 helper for obtaining the clock
media: i2c: gc2145: Use the v4l2 helper for obtaining the clock
media: i2c: hi846: Use the v4l2 helper for obtaining the clock
media: i2c: imx214: Use the v4l2 helper for obtaining the clock
media: i2c: imx219: Use the v4l2 helper for obtaining the clock

media: i2c: imx283: Use the v4l2 helper for obtaining the clock
media: i2c: imx290: Use the v4l2 helper for obtaining the clock
media: i2c: imx296: Use the v4l2 helper for obtaining the clock
media: i2c: imx334: Use the v4l2 helper for obtaining the clock
media: i2c: imx335: Use the v4l2 helper for obtaining the clock
media: i2c: imx412: Use the v4l2 helper for obtaining the clock
media: i2c: imx415: Use the v4l2 helper for obtaining the clock
media: i2c: max2175: Use the v4l2 helper for obtaining the clock

media: i2c: mt9m001: Use the v4l2 helper for obtaining the clock
media: i2c: mt9m111: Use the v4l2 helper for obtaining the clock
media: i2c: mt9m114: Use the v4l2 helper for obtaining the clock
media: i2c: mt9p031: Use the v4l2 helper for obtaining the clock
media: i2c: mt9t112: Use the v4l2 helper for obtaining the clock
media: i2c: mt9v032: Use the v4l2 helper for obtaining the clock
media: i2c: mt9v111: Use the v4l2 helper for obtaining the clock
media: i2c: ov02a10: Use the v4l2 helper for obtaining the clock
media: i2c: ov2659: Use the v4l2 helper for obtaining the clock
media: i2c: ov2685: Use the v4l2 helper for obtaining the clock
media: i2c: ov5640: Use the v4l2 helper for obtaining the clock
media: i2c: ov5645: Use the v4l2 helper for obtaining the clock
media: i2c: ov5647: Use the v4l2 helper for obtaining the clock
media: i2c: ov5648: Use the v4l2 helper for obtaining the clock
media: i2c: ov5695: Use the v4l2 helper for obtaining the clock
media: i2c: ov64a40: Use the v4l2 helper for obtaining the clock
media: i2c: ov6650: Use the v4l2 helper for obtaining the clock
media: i2c: ov7740: Use the v4l2 helper for obtaining the clock
media: i2c: ov8856: Use the v4l2 helper for obtaining the clock
media: i2c: ov8858: Use the v4l2 helper for obtaining the clock
media: i2c: ov8865: Use the v4l2 helper for obtaining the clock
media: i2c: ov9282: Use the v4l2 helper for obtaining the clock

media: i2c: ov9640: Use the v4l2 helper for obtaining the clock
media: i2c: ov9650: Use the v4l2 helper for obtaining the clock
media: i2c: s5c73m3: Use the v4l2 helper for obtaining the clock
media: i2c: s5k5baf: Use the v4l2 helper for obtaining the clock
media: i2c: s5k6a3: Use the v4l2 helper for obtaining the clock
media: i2c: st-mipid02: Use the v4l2 helper for obtaining the clock
media: i2c: tc358743: Use the v4l2 helper for obtaining the clock
media: i2c: tc358746: Use the v4l2 helper for obtaining the clock

media: i2c: thp7312: Use the v4l2 helper for obtaining the clock

media: i2c: vd55g1: Use the v4l2 helper for obtaining the clock
media: i2c: vd56g3: Use the v4l2 helper for obtaining the clock
media: i2c: vgxy61: Use the v4l2 helper for obtaining the clock
media: i2c: ov2680: Use the v4l2 helper for obtaining the clock

 .../driver-api/media/camera-sensor.rst        |  3 +-
 drivers/media/i2c/ar0521.c                    |  2 +-
 drivers/media/i2c/ds90ub913.c                 |  2 +-
 drivers/media/i2c/ds90ub960.c                 |  2 +-
 drivers/media/i2c/et8ek8/et8ek8_driver.c      |  2 +-
 drivers/media/i2c/gc05a2.c                    |  2 +-
 drivers/media/i2c/gc08a3.c                    |  2 +-
 drivers/media/i2c/gc2145.c                    |  2 +-
 drivers/media/i2c/hi846.c                     |  2 +-
 drivers/media/i2c/imx214.c                    |  2 +-
 drivers/media/i2c/imx219.c                    |  2 +-
 drivers/media/i2c/imx283.c                    |  2 +-
 drivers/media/i2c/imx290.c                    |  2 +-
 drivers/media/i2c/imx296.c                    |  2 +-
 drivers/media/i2c/imx334.c                    |  2 +-
 drivers/media/i2c/imx335.c                    |  2 +-
 drivers/media/i2c/imx412.c                    |  2 +-
 drivers/media/i2c/imx415.c                    |  2 +-
 drivers/media/i2c/max2175.c                   |  2 +-
 drivers/media/i2c/mt9m001.c                   |  2 +-
 drivers/media/i2c/mt9m111.c                   |  2 +-
 drivers/media/i2c/mt9m114.c                   |  2 +-
 drivers/media/i2c/mt9p031.c                   |  2 +-
 drivers/media/i2c/mt9t112.c                   |  2 +-
 drivers/media/i2c/mt9v032.c                   |  2 +-
 drivers/media/i2c/mt9v111.c                   |  2 +-
 drivers/media/i2c/ov02a10.c                   |  2 +-
 drivers/media/i2c/ov2659.c                    |  2 +-
 drivers/media/i2c/ov2680.c                    | 27 +++-------
 drivers/media/i2c/ov2685.c                    |  2 +-
 drivers/media/i2c/ov5640.c                    |  2 +-
 drivers/media/i2c/ov5645.c                    |  2 +-
 drivers/media/i2c/ov5647.c                    |  2 +-
 drivers/media/i2c/ov5648.c                    |  2 +-
 drivers/media/i2c/ov5695.c                    |  2 +-
 drivers/media/i2c/ov64a40.c                   |  2 +-
 drivers/media/i2c/ov6650.c                    |  2 +-
 drivers/media/i2c/ov7740.c                    |  2 +-
 drivers/media/i2c/ov8856.c                    |  2 +-
 drivers/media/i2c/ov8858.c                    |  2 +-
 drivers/media/i2c/ov8865.c                    | 32 ++----------
 drivers/media/i2c/ov9282.c                    |  2 +-
 drivers/media/i2c/ov9640.c                    |  2 +-
 drivers/media/i2c/ov9650.c                    |  2 +-
 drivers/media/i2c/s5c73m3/s5c73m3-core.c      |  2 +-
 drivers/media/i2c/s5k5baf.c                   |  2 +-
 drivers/media/i2c/s5k6a3.c                    |  2 +-
 drivers/media/i2c/st-mipid02.c                |  2 +-
 drivers/media/i2c/tc358743.c                  |  2 +-
 drivers/media/i2c/tc358746.c                  |  2 +-
 drivers/media/i2c/thp7312.c                   |  2 +-
 drivers/media/i2c/vd55g1.c                    |  2 +-
 drivers/media/i2c/vd56g3.c                    |  2 +-
 drivers/media/i2c/vgxy61.c                    |  2 +-
 drivers/media/v4l2-core/v4l2-common.c         | 49 +++++++++++++++++++
 include/media/v4l2-common.h                   | 25 ++++++++++
 56 files changed, 136 insertions(+), 102 deletions(-)

Hello everyone,

Here is my v1 for the new helper v4l2_devm_sensor_clk_get()

Any testing of the patches is GREATLY APPRECIATED! Especially the two drivers with the special ACPI case:
1) OV8865
2) OV2680

Background
----------

A reference to the clock producer is not available to the kernel in ACPI-based platforms but the sensor drivers still need them.

devm_clk_get() will return an error and the probe function will fail.

Solution
--------

Introduce a generic helper for v4l2 sensor drivers on both DT- and ACPI-based platforms.

This helper behaves the same as clk_get_optional() except where there is no clock producer like in ACPI-based platforms.

For ACPI-based platforms the function will read the "clock-frequency" ACPI _DSD property and register a fixed frequency clock with the frequency indicated in the property.

Solution for special ACPI case
------------------------------

This function also handles the special ACPI-based system case where:

1) The clock-frequency _DSD property is present.
2) A reference to the clock producer is present, where the clock is provided by a camera sensor PMIC driver (e.g. int3472/tps68470.c)

In this case try to set the clock-frequency value to the provided clock.

RFC History
-----------

RFC v4 -> RFC v5:
Suggested by Arnd Bergmann:
- removed IS_REACHABLE(CONFIG_COMMON_CLK). IS_REACHABLE() is actually
discouraged [1]. COFIG_COMMON_CLK is a bool, so IS_ENABLED() will be the
right solution here
Suggested by Hans de Goede:
- added handling for the special ACPI-based system case, where
both a reference to the clock-provider and the _DSD
clock-frequency are present.
- updated the function's kernel-doc and the commit msg
to mention this special case.
Link RFC v4: https://lore.kernel.org/linux-media/[email protected]/
[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/Documentation/kbuild/kconfig-language.rst?h=next-20250513&id=700bd25bd4f47a0f4e02e0a25dde05f1a6b16eea

RFC v3 -> RFC v4:
Suggested by Laurent:
- removed the #ifdef to use IS_REACHABLE(CONFIG_COMMON_CLK)
- changed to kasprintf() to allocate the clk name when id is NULL and used the __free(kfree) scope-based cleanup helper when
defining the variable to hold the allocated name
Link v3: https://lore.kernel.org/linux-media/[email protected]/

RFC v2 -> RFC v3:
- Added #ifdef CONFIG_COMMON_CLK for the ACPI case
Link v2: https://lore.kernel.org/linux-media/[email protected]/

RFC v1 -> RFC v2:
Suggested by Sakari:
- removed clk_name
- removed the IS_ERR() check
- improved the kernel-doc comment and commit msg
Link v1: https://lore.kernel.org/linux-media/[email protected]

Mehdi Djait (55):
media: v4l2-common: Add a helper for obtaining the clock producer
Documentation: media: camera-sensor: Mention
v4l2_devm_sensor_clk_get() for obtaining the clock
media: i2c: ar0521: Use the v4l2 helper for obtaining the clock
media: i2c: ds90ub913: Use the v4l2 helper for obtaining the clock
media: i2c: ds90ub960: Use the v4l2 helper for obtaining the clock
media: i2c: et8ek8: Use the v4l2 helper for obtaining the clock
media: i2c: gc05a2: Use the v4l2 helper for obtaining the clock
media: i2c: gc08a3: Use the v4l2 helper for obtaining the clock
media: i2c: gc2145: Use the v4l2 helper for obtaining the clock
media: i2c: hi846: Use the v4l2 helper for obtaining the clock
media: i2c: imx214: Use the v4l2 helper for obtaining the clock
media: i2c: imx219: Use the v4l2 helper for obtaining the clock
media: i2c: imx283: Use the v4l2 helper for obtaining the clock
media: i2c: imx290: Use the v4l2 helper for obtaining the clock
media: i2c: imx296: Use the v4l2 helper for obtaining the clock
media: i2c: imx334: Use the v4l2 helper for obtaining the clock
media: i2c: imx335: Use the v4l2 helper for obtaining the clock
media: i2c: imx412: Use the v4l2 helper for obtaining the clock
media: i2c: imx415: Use the v4l2 helper for obtaining the clock
media: i2c: max2175: Use the v4l2 helper for obtaining the clock
media: i2c: mt9m001: Use the v4l2 helper for obtaining the clock
media: i2c: mt9m111: Use the v4l2 helper for obtaining the clock
media: i2c: mt9m114: Use the v4l2 helper for obtaining the clock
media: i2c: mt9p031: Use the v4l2 helper for obtaining the clock
media: i2c: mt9t112: Use the v4l2 helper for obtaining the clock
media: i2c: mt9v032: Use the v4l2 helper for obtaining the clock
media: i2c: mt9v111: Use the v4l2 helper for obtaining the clock
media: i2c: ov02a10: Use the v4l2 helper for obtaining the clock
media: i2c: ov2659: Use the v4l2 helper for obtaining the clock
media: i2c: ov2685: Use the v4l2 helper for obtaining the clock
media: i2c: ov5640: Use the v4l2 helper for obtaining the clock
media: i2c: ov5645: Use the v4l2 helper for obtaining the clock
media: i2c: ov5647: Use the v4l2 helper for obtaining the clock
media: i2c: ov5648: Use the v4l2 helper for obtaining the clock
media: i2c: ov5695: Use the v4l2 helper for obtaining the clock
media: i2c: ov64a40: Use the v4l2 helper for obtaining the clock
media: i2c: ov6650: Use the v4l2 helper for obtaining the clock
media: i2c: ov7740: Use the v4l2 helper for obtaining the clock
media: i2c: ov8856: Use the v4l2 helper for obtaining the clock
media: i2c: ov8858: Use the v4l2 helper for obtaining the clock
media: i2c: ov8865: Use the v4l2 helper for obtaining the clock
media: i2c: ov9282: Use the v4l2 helper for obtaining the clock
media: i2c: ov9640: Use the v4l2 helper for obtaining the clock
media: i2c: ov9650: Use the v4l2 helper for obtaining the clock
media: i2c: s5c73m3: Use the v4l2 helper for obtaining the clock
media: i2c: s5k5baf: Use the v4l2 helper for obtaining the clock
media: i2c: s5k6a3: Use the v4l2 helper for obtaining the clock
media: i2c: st-mipid02: Use the v4l2 helper for obtaining the clock
media: i2c: tc358743: Use the v4l2 helper for obtaining the clock
media: i2c: tc358746: Use the v4l2 helper for obtaining the clock
media: i2c: thp7312: Use the v4l2 helper for obtaining the clock
media: i2c: vd55g1: Use the v4l2 helper for obtaining the clock
media: i2c: vd56g3: Use the v4l2 helper for obtaining the clock
media: i2c: vgxy61: Use the v4l2 helper for obtaining the clock
media: i2c: ov2680: Use the v4l2 helper for obtaining the clock

 .../driver-api/media/camera-sensor.rst        |  3 +-
 drivers/media/i2c/ar0521.c                    |  2 +-
 drivers/media/i2c/ds90ub913.c                 |  2 +-
 drivers/media/i2c/ds90ub960.c                 |  2 +-
 drivers/media/i2c/et8ek8/et8ek8_driver.c      |  2 +-
 drivers/media/i2c/gc05a2.c                    |  2 +-
 drivers/media/i2c/gc08a3.c                    |  2 +-
 drivers/media/i2c/gc2145.c                    |  2 +-
 drivers/media/i2c/hi846.c                     |  2 +-
 drivers/media/i2c/imx214.c                    |  2 +-
 drivers/media/i2c/imx219.c                    |  2 +-
 drivers/media/i2c/imx283.c                    |  2 +-
 drivers/media/i2c/imx290.c                    |  2 +-
 drivers/media/i2c/imx296.c                    |  2 +-
 drivers/media/i2c/imx334.c                    |  2 +-
 drivers/media/i2c/imx335.c                    |  2 +-
 drivers/media/i2c/imx412.c                    |  2 +-
 drivers/media/i2c/imx415.c                    |  2 +-
 drivers/media/i2c/max2175.c                   |  2 +-
 drivers/media/i2c/mt9m001.c                   |  2 +-
 drivers/media/i2c/mt9m111.c                   |  2 +-
 drivers/media/i2c/mt9m114.c                   |  2 +-
 drivers/media/i2c/mt9p031.c                   |  2 +-
 drivers/media/i2c/mt9t112.c                   |  2 +-
 drivers/media/i2c/mt9v032.c                   |  2 +-
 drivers/media/i2c/mt9v111.c                   |  2 +-
 drivers/media/i2c/ov02a10.c                   |  2 +-
 drivers/media/i2c/ov2659.c                    |  2 +-
 drivers/media/i2c/ov2680.c                    | 27 +++-------
 drivers/media/i2c/ov2685.c                    |  2 +-
 drivers/media/i2c/ov5640.c                    |  2 +-
 drivers/media/i2c/ov5645.c                    |  2 +-
 drivers/media/i2c/ov5647.c                    |  2 +-
 drivers/media/i2c/ov5648.c                    |  2 +-
 drivers/media/i2c/ov5695.c                    |  2 +-
 drivers/media/i2c/ov64a40.c                   |  2 +-
 drivers/media/i2c/ov6650.c                    |  2 +-
 drivers/media/i2c/ov7740.c                    |  2 +-
 drivers/media/i2c/ov8856.c                    |  2 +-
 drivers/media/i2c/ov8858.c                    |  2 +-
 drivers/media/i2c/ov8865.c                    | 32 ++----------
 drivers/media/i2c/ov9282.c                    |  2 +-
 drivers/media/i2c/ov9640.c                    |  2 +-
 drivers/media/i2c/ov9650.c                    |  2 +-
 drivers/media/i2c/s5c73m3/s5c73m3-core.c      |  2 +-
 drivers/media/i2c/s5k5baf.c                   |  2 +-
 drivers/media/i2c/s5k6a3.c                    |  2 +-
 drivers/media/i2c/st-mipid02.c                |  2 +-
 drivers/media/i2c/tc358743.c                  |  2 +-
 drivers/media/i2c/tc358746.c                  |  2 +-
 drivers/media/i2c/thp7312.c                   |  2 +-
 drivers/media/i2c/vd55g1.c                    |  2 +-
 drivers/media/i2c/vd56g3.c                    |  2 +-
 drivers/media/i2c/vgxy61.c                    |  2 +-
 drivers/media/v4l2-core/v4l2-common.c         | 49 +++++++++++++++++++
 include/media/v4l2-common.h                   | 25 ++++++++++
 56 files changed, 136 insertions(+), 102 deletions(-)

Hi Mehdi,

Thanks for your work!

Quoted 19 lines · Mehdi Djait

Hello everyone,

Here is my v1 for the new helper v4l2_devm_sensor_clk_get()

Any testing of the patches is GREATLY APPRECIATED! Especially the two drivers with the special ACPI case:
1) OV8865
2) OV2680

Background
----------

A reference to the clock producer is not available to the kernel in ACPI-based platforms but the sensor drivers still need them.

devm_clk_get() will return an error and the probe function will fail.

Quoted 5 lines

Solution
--------

Introduce a generic helper for v4l2 sensor drivers on both DT- and ACPI-based platforms.

Out of curiosity: How is this problem specific to V4L2? Does one need a similar helper in other subsystems?

Hello everyone,

Here is my v1 for the new helper v4l2_devm_sensor_clk_get()

Any testing of the patches is GREATLY APPRECIATED! Especially the two drivers with the special ACPI case:
1) OV8865
2) OV2680

Background
----------

A reference to the clock producer is not available to the kernel in ACPI-based platforms but the sensor drivers still need them.

devm_clk_get() will return an error and the probe function will fail.

Solution
--------

Introduce a generic helper for v4l2 sensor drivers on both DT- and ACPI-based platforms.

This helper behaves the same as clk_get_optional() except where there is no clock producer like in ACPI-based platforms.

For ACPI-based platforms the function will read the "clock-frequency" ACPI _DSD property and register a fixed frequency clock with the frequency indicated in the property.

Solution for special ACPI case
------------------------------

This function also handles the special ACPI-based system case where:

1) The clock-frequency _DSD property is present.
2) A reference to the clock producer is present, where the clock is provided by a camera sensor PMIC driver (e.g. int3472/tps68470.c)

In this case try to set the clock-frequency value to the provided clock.

RFC History
-----------

RFC v4 -> RFC v5:
Suggested by Arnd Bergmann:
- removed IS_REACHABLE(CONFIG_COMMON_CLK). IS_REACHABLE() is actually
discouraged [1]. COFIG_COMMON_CLK is a bool, so IS_ENABLED() will be the
right solution here
Suggested by Hans de Goede:
- added handling for the special ACPI-based system case, where
both a reference to the clock-provider and the _DSD
clock-frequency are present.
- updated the function's kernel-doc and the commit msg
to mention this special case.
Link RFC v4: https://lore.kernel.org/linux-media/[email protected]/
[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/Documentation/kbuild/kconfig-language.rst?h=next-20250513&id=700bd25bd4f47a0f4e02e0a25dde05f1a6b16eea

RFC v3 -> RFC v4:
Suggested by Laurent:
- removed the #ifdef to use IS_REACHABLE(CONFIG_COMMON_CLK)
- changed to kasprintf() to allocate the clk name when id is NULL and used the __free(kfree) scope-based cleanup helper when
defining the variable to hold the allocated name
Link v3: https://lore.kernel.org/linux-media/[email protected]/

RFC v2 -> RFC v3:
- Added #ifdef CONFIG_COMMON_CLK for the ACPI case
Link v2: https://lore.kernel.org/linux-media/[email protected]/

RFC v1 -> RFC v2:
Suggested by Sakari:
- removed clk_name
- removed the IS_ERR() check
- improved the kernel-doc comment and commit msg
Link v1: https://lore.kernel.org/linux-media/[email protected]

Mehdi Djait (55):
media: v4l2-common: Add a helper for obtaining the clock producer
Documentation: media: camera-sensor: Mention
v4l2_devm_sensor_clk_get() for obtaining the clock
media: i2c: imx219: Use the v4l2 helper for obtaining the clock
media: i2c: mt9p031: Use the v4l2 helper for obtaining the clock
media: i2c: ov2659: Use the v4l2 helper for obtaining the clock
media: i2c: ov2685: Use the v4l2 helper for obtaining the clock
media: i2c: ov5640: Use the v4l2 helper for obtaining the clock
media: i2c: ov5645: Use the v4l2 helper for obtaining the clock