[PATCH v2] media: i2c: gc0310: Use devm_v4l2_sensor_clk_get()

[Sanjay Chitroda <sanjayembeddedse@gmail.com>]

Several camera sensor drivers access the "clock-frequency" property
directly to retrieve the external clock rate or handle the external
clock manually in the driver. While this is valid on a subset of ACPI
platforms, implementing this logic directly in drivers is deprecated
and can lead to inconsistent behaviour across drivers.

This driver supports ACPI platforms only. It currently retrieves the
external clock rate from the "clock-frequency" property and fails
probing if the rate does not match the expected value, which is the
correct policy for ACPI platforms.

Switch to using the devm_v4l2_sensor_clk_get() helper to standardise
clock handling. This preserves the existing behaviour on ACPI
platforms that specify a clock-frequency property without providing
a clock. On platforms that provide a clock, the helper will program
the clock to the rate specified by clock-frequency, which is also
consistent with the driver's expectations.

Reviewed-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Signed-off-by: Sanjay Chitroda <sanjayembeddedse@gmail.com>

---
Changes in v2:
- With input from Hans de drop first 2 changes and rebase 3rd change
  along with reviewed tag on top of mainline tree and v7.2-rc2 commit tag.
- Link to v1: https://lore.kernel.org/20260401181657.654055-1-sanjayembedded@gmail.com
---
 drivers/media/i2c/gc0310.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/drivers/media/i2c/gc0310.c b/drivers/media/i2c/gc0310.c
index 7af4d66f42a0..754e82ad50ae 100644
--- a/drivers/media/i2c/gc0310.c
+++ b/drivers/media/i2c/gc0310.c
@@ -6,6 +6,7 @@
  * Copyright (c) 2023-2025 Hans de Goede <hansg@kernel.org>
  */
 
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/gpio/consumer.h>
@@ -84,6 +85,8 @@
 #define to_gc0310_sensor(x) container_of(x, struct gc0310_device, sd)
 
 struct gc0310_device {
+	struct clk *clk;
+
 	struct v4l2_subdev sd;
 	struct media_pad pad;
 
@@ -635,7 +638,6 @@ static int gc0310_check_hwcfg(struct device *dev)
 	};
 	struct fwnode_handle *ep_fwnode;
 	unsigned long link_freq_bitmap;
-	u32 mclk;
 	int ret;
 
 	/*
@@ -647,21 +649,6 @@ static int gc0310_check_hwcfg(struct device *dev)
 		return dev_err_probe(dev, -EPROBE_DEFER,
 				     "waiting for fwnode graph endpoint\n");
 
-	ret = fwnode_property_read_u32(dev_fwnode(dev), "clock-frequency",
-				       &mclk);
-	if (ret) {
-		fwnode_handle_put(ep_fwnode);
-		return dev_err_probe(dev, ret,
-				     "reading clock-frequency property\n");
-	}
-
-	if (mclk != GC0310_MCLK_FREQ) {
-		fwnode_handle_put(ep_fwnode);
-		return dev_err_probe(dev, -EINVAL,
-				     "external clock %u is not supported\n",
-				     mclk);
-	}
-
 	ret = v4l2_fwnode_endpoint_alloc_parse(ep_fwnode, &bus_cfg);
 	fwnode_handle_put(ep_fwnode);
 	if (ret)
@@ -685,6 +672,7 @@ static int gc0310_check_hwcfg(struct device *dev)
 static int gc0310_probe(struct i2c_client *client)
 {
 	struct gc0310_device *sensor;
+	unsigned long freq;
 	int ret;
 
 	ret = gc0310_check_hwcfg(&client->dev);
@@ -695,6 +683,16 @@ static int gc0310_probe(struct i2c_client *client)
 	if (!sensor)
 		return -ENOMEM;
 
+	sensor->clk = devm_v4l2_sensor_clk_get(&client->dev, NULL);
+	if (IS_ERR(sensor->clk))
+		return dev_err_probe(&client->dev, PTR_ERR(sensor->clk),
+				     "failed to get clock\n");
+
+	freq = clk_get_rate(sensor->clk);
+	if (freq != GC0310_MCLK_FREQ)
+		return dev_err_probe(&client->dev, -EINVAL,
+				     "external clock %lu is not supported\n", freq);
+
 	sensor->reset = devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_HIGH);
 	if (IS_ERR(sensor->reset)) {
 		return dev_err_probe(&client->dev, PTR_ERR(sensor->reset),
-- 
--