# CCI operation speed

Source: [https://docs.qualcomm.com/doc/80-88500-1/topic/65_Configure_CCI_operation_speed.html](https://docs.qualcomm.com/doc/80-88500-1/topic/65_Configure_CCI_operation_speed.html)

Following the I^2^C specification, CCI of the device can operate on the following
      frequencies:

- 100 kHz (STANDARD)
- 400 kHz (FAST)
- 1 MHz (FAST PLUS)

The I^2^C frequency mode controls the operation speed. For custom mode, the CCI tuning
      configuration information is available at either of the following paths:
- Linux Ubuntu:
            src\kernel\msm-5.4\arch\arm64\boot\dts\vendor\qcom\camera\XXX-camera.dtsi
- Linux Embedded:
            src\kernel\msm-5.15\arch\arm64\boot\dts\vendor\qcom\camera\XXX-camera.dtsi

Also, see vendor\qcom\proprietary\camera-devicetree\XXX-camera.dtsi.

Example CCI configuration:

    i2c_freq_custom: qcom,i2c_custom_mode { qcom,hw-thigh = <38>;
    qcom,hw-tlow = <56>;
    qcom,hw-tsu-sto = <40>;
    qcom,hw-tsu-sta = <40>;
    qcom,hw-thd-dat = <22>;
    qcom,hw-thd-sta = <35>;
    qcom,hw-tbuf = <62>;
    qcom,hw-scl-stretch-en = <1>;
    qcom,hw-trdhld = <6>;
    qcom,hw-tsp = <3>;
    qcom,cci-clk-src = <37500000>; status = "ok";
    };
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If a custom CCI configuration is used, then the speed of I^2^C frequency information is
      calculated as:

CCI clock = (src clock)/(hw\_thigh+ hw\_tlow)

Because the CCI clock frequency is typically 19.2 MHz, the standard CCI frequency case is:

CCI clock = 19.2 MHz/(78 + 114) = 100 kHz

When there is no CCI hardware, or when QUP is used for I^2^C, the QUP speed is set to
      either 100 kHz or 400 kHz from the DTSI file. Use one of the supported operation
      frequencies.

**Parent Topic:** [Sensor hardware configuration](https://docs.qualcomm.com/doc/80-88500-1/topic/62_Sensor_hardware_configuration.html)

Last Published: Aug 18, 2023

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