Change freqency of mclk for ov5640_mipi with imx6dl

[dongpv]

Hi,

Currently, We're doing EMC testing for our product that using imx6dl and camera ov5640.

Now, we want to change frequency of mclk for ov5640_mipi. It's default value is 24Mhz.

I tried change mclk with many difference value from device tree but it still got measuring result from Oscilloscope is 24Mhz.

    ov564x_mipi: ov564x_mipi@3c { /* i2c2 driver */
        compatible = "ovti,ov564x_mipi";
        reg = <0x3c>;
        clocks = <&clks 201>;
        clock-names = "csi_mclk";
        DOVDD-supply = <&vgen4_reg>; /* 1.8v */
        AVDD-supply = <&vgen3_reg>;  /* 2.8v, rev C board is VGEN3
                        rev B board is VGEN5 */
        DVDD-supply = <&vgen2_reg>;  /* 1.5v*/
        pwn-gpios = <&gpio1 19 1>;   /* active low: SD1_CLK */
        rst-gpios = <&gpio1 20 0>;   /* active high: SD1_DAT2 */
        csi_id = <1>;
        mclk = <12000000>;  /* default is 24000000 */
        mclk_source = <0>;
    };

My question is if above solutions is not correct . So, is there any way to change this frequency of mclk?

Kernel version we 're using is Linux 4.1.15.

Thanks & Best Regards,

Dong

[igorpadykov]

Hi Dong

clocks = <&clks 201>;  is defined in
linux/include/dt-bindings/clock/imx6qdl-clock.h

also one can add cko2_podf, (it is defined in imx6qdl-clock.h as #define IMX6QDL_CLK_CKO2_PODF            199 )

and described in sect.18.6.21 CCM Clock Output Source Register (CCM_CCOSR) i.MX6Q RM

please check linux/arch/arm/mach-imx/clk-imx6q.c
http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/tree/arch/arm/mach-imx/clk-imx6q.c?h=imx...
    imx_clk_set_parent(clk[IMX6QDL_CLK_CKO2_SEL], clk[IMX6QDL_CLK_OSC]);
    imx_clk_set_parent(clk[IMX6QDL_CLK_CKO], clk[IMX6QDL_CLK_CKO2]);

Best regards
igor
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[dongpv]

Hi igor,

Sorry , I not really clearly how to change that speed on ov5640_mipi? could you please explain more about that solution, where  I should change the value of speed so that it can reduce frequency of mipi_ov5640. :smileyhappy: Thanks very much for your respond !

Best regards,

Dong

[dongpv]

Hi Igor,

I tried to change clock from 201 to 199 like that clocks = <&clks 199> from device tree but camera can't work, there are no output for mclk also.

I don't know it's correct with your suggestion or not?

Thanks

Dong