How to disable MCLK ?

[khang_letruong]

Dear Community,

To rule out the impact of MCLK frequency to other high speed interfaces on our custom PCB based on iMX8MP, we have a need to enable/disable the MIPI-CSI2 camera driver in order to enable /disable the MCLK clock:

I re-built the ov5640_mipi_v2.c as loadable kernel module :

diff --git a/arch/arm64/configs/imx_v8_defconfig b/arch/arm64/configs/imx_v8_defconfig
index a8a46508482d..a096230294d3 100644
--- a/arch/arm64/configs/imx_v8_defconfig
+++ b/arch/arm64/configs/imx_v8_defconfig
@@ -528,7 +528,7 @@ CONFIG_VIDEO_MXC_CAPTURE=y
 CONFIG_VIDEO_MX8_CAPTURE=y
 CONFIG_VIDEO_MXC_CSI_CAMERA=y
 CONFIG_MXC_MIPI_CSI=y
-CONFIG_MXC_CAMERA_OV5640_MIPI_V2=y
+CONFIG_MXC_CAMERA_OV5640_MIPI_V2=m
 CONFIG_V4L_MEM2MEM_DRIVERS=y
 CONFIG_SDR_PLATFORM_DRIVERS=y
 CONFIG_VIDEO_IMX219=m

I saw the in remove() function, clk_disable_unprepare(sensor->sensor_clk) is called. But the 24-MHz MCLK  still persists after rmmod.

static int ov5640_remove(struct i2c_client *client)
{
        struct v4l2_subdev *sd = i2c_get_clientdata(client);
        struct ov5640 *sensor = to_ov5640(client);

        v4l2_async_unregister_subdev(sd);

        clk_disable_unprepare(sensor->sensor_clk);

        ov5640_power_down(sensor, 1);

        ov5640_regualtor_disable();

        return 0;
}

I would like to know how to disable it completely during the removing of the module, please?

Thanks in advance and best regards,
Khang

[joanxie]

refer to the schematic

the dts file set this already,

pinctrl_csi_mclk: csi_mclk_grp {
fsl,pins = <
MX8MP_IOMUXC_GPIO1_IO15__CCM_CLKO2 0x50
>;
};

[khang_letruong]

Hi @joanxie ,

Sorry that I did not catch what you meant.Did you mean that MCLK was enabled permanently by the relevant lines in dts file ?

I would like to know if there's any way to disable the MCLK  in runtime, please ?

Best Regards,

Khang

[joanxie]

the HW and dts I shared with you, just reminder you checking if you disable it correctly, how did you disable this

[joanxie]

how did you set in the dts file? did you disable this camera in the dts? if yes, did you still measure the mclk 24M from this pin?