On Mon, Nov 02, 2020 at 05:08:47PM +0200, Sakari Ailus wrote:

Hi Krysztof,

On Mon, Oct 19, 2020 at 07:26:17PM +0200, Krzysztof Kozlowski wrote:

quoted

The IMX258 sensor driver checked in device properties for a
clock-frequency property which actually does not mean that the clock is
really running such frequency or is it even enabled.

Get the provided clock and check it frequency.  If none is provided,
fall back to old property.

Enable the clock when accessing the IMX258 registers and when streaming
starts with runtime PM.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

---

Changes since v4:
1. Add missing imx258_power_off.

Changes since v3:
1. None

Changes since v2:
1. Do not try to set drvdata, wrap lines.
2. Use dev_dbg.

Changes since v1:
1. Use runtime PM for clock toggling
---
 drivers/media/i2c/imx258.c | 73 +++++++++++++++++++++++++++++++++-----
 1 file changed, 64 insertions(+), 9 deletions(-)

diff --git a/drivers/media/i2c/imx258.c b/drivers/media/i2c/imx258.c
index ae183b0dbba9..038115471f17 100644
--- a/drivers/media/i2c/imx258.c
+++ b/drivers/media/i2c/imx258.c

@@ -2,6 +2,7 @@
 // Copyright (C) 2018 Intel Corporation
 
 #include <linux/acpi.h>
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/module.h>

@@ -68,6 +69,9 @@
 #define REG_CONFIG_MIRROR_FLIP		0x03
 #define REG_CONFIG_FLIP_TEST_PATTERN	0x02
 
+/* Input clock frequency in Hz */
+#define IMX258_INPUT_CLOCK_FREQ		19200000
+
 struct imx258_reg {
 	u16 address;
 	u8 val;

@@ -610,6 +614,8 @@ struct imx258 {
 
 	/* Streaming on/off */
 	bool streaming;
+
+	struct clk *clk;
 };
 
 static inline struct imx258 *to_imx258(struct v4l2_subdev *_sd)

@@ -972,6 +978,29 @@ static int imx258_stop_streaming(struct imx258 *imx258)
 	return 0;
 }
 
+static int imx258_power_on(struct device *dev)
+{
+	struct v4l2_subdev *sd = dev_get_drvdata(dev);
+	struct imx258 *imx258 = to_imx258(sd);
+	int ret;
+
+	ret = clk_prepare_enable(imx258->clk);
+	if (ret)
+		dev_err(dev, "failed to enable clock\n");
+
+	return ret;
+}
+
+static int imx258_power_off(struct device *dev)
+{
+	struct v4l2_subdev *sd = dev_get_drvdata(dev);
+	struct imx258 *imx258 = to_imx258(sd);
+
+	clk_disable_unprepare(imx258->clk);
+
+	return 0;
+}
+
 static int imx258_set_stream(struct v4l2_subdev *sd, int enable)
 {
 	struct imx258 *imx258 = to_imx258(sd);

@@ -1199,9 +1228,28 @@ static int imx258_probe(struct i2c_client *client)
 	int ret;
 	u32 val = 0;
 
-	device_property_read_u32(&client->dev, "clock-frequency", &val);
-	if (val != 19200000)
-		return -EINVAL;
+	imx258 = devm_kzalloc(&client->dev, sizeof(*imx258), GFP_KERNEL);
+	if (!imx258)
+		return -ENOMEM;
+
+	imx258->clk = devm_clk_get_optional(&client->dev, NULL);
+	if (!imx258->clk) {
+		dev_dbg(&client->dev,
+			"no clock provided, using clock-frequency property\n");
+
+		device_property_read_u32(&client->dev, "clock-frequency", &val);
+		if (val != IMX258_INPUT_CLOCK_FREQ)
+			return -EINVAL;
+	} else if (IS_ERR(imx258->clk)) {
+		return dev_err_probe(&client->dev, PTR_ERR(imx258->clk),
+				     "error getting clock\n");
+	} else {
+		if (clk_get_rate(imx258->clk) != IMX258_INPUT_CLOCK_FREQ) {

Please move the check outside the conditional block. May be a separate
patch if you like.

OK

Best regards,
Krzysztof