IMX6 27MHz on CSI_MCLK

[umit_kayacik]

Hi,

I am tring to take 27Mhz from IMX6 Sabresd board from GPIO_0_CLKO pin.

How can i do that? I guess 24Mhz is default set in DTS but i couldnt see any clock in this pin on ossiloscope? Do i need to change DTS also?

Cheers,

Umit.

[igorpadykov]

Hi Umit

24MHz is defined in linux/arch/arm/boot/dts/imx6qdl-sabresd.dtsi :

ov564x: ov564x@3c

imx6qdl-sabresd.dtsi\dts\boot\arm\arch - linux-imx - i.MX Linux kernel 

and one can test check this clock on NXP Sabre board with Demo Images from

i.MX Software | NXP 

OV564x drivers are described in sect.6.1.2 Omnivision Camera attached Linux Manual.

For obtaining 27Mhz it is necessary to modify driver or better add CCM_CCOSR initialization to uboot,

set some suitable parent clock (probably changing some PLL frequency), so 27Mhz clock

can be divided from parent clock.

Best regards
igor
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[umit_kayacik]

Hi Igor,

I even download sample images for older version (L4.1.15_1.0.0-ga_images_MX6QDLSOLO) for SabreSD, i cannot still see the 24Mhz on "GPIO_0_CLKO". 

Do you want me to test spesific version of kernel that CSI_MCLK is generated correctly?

Note : prev version of kernel was yocto somo 4.14.98-imx_4.14.98_2.0.0_ga+g5d6cbe

Umit

[igorpadykov]

Hi Umit

what board tested, custom or i.MX6Q Sabre SD board.

MCLK configuration can be debugged in camera driver, for example in

linux/drivers/media/platform/mxc/capture/ov5640.c

ov5640.c\capture\mxc\platform\media\drivers - linux-imx - i.MX Linux kernel 

Linux configuration is described in sect.6.1.2 Omnivision Camera

attached Linux Manual.

Uboot MCLK (CKO1) configuration example:

uboot-imx/tree/board/toradex/colibri_imx6/colibri_imx6.c

colibri_imx6.c\colibri_imx6\toradex\board - uboot-imx - i.MX U-Boot 

Best regards
igor

[umit_kayacik]

I am using i.MX6Q Sabre SD evaluation board. I ve just download the image and create a sdcard from it. 

But i cannot see the CSI_MCLK on the above pin. Actually i dont have camera module(OV564x) so it is not connected to board.

I simply want to see 24Mhz (then i will try to see 27mhz) CSI_MCLK pin(GPIO_0_CLKO).

Umit.

[igorpadykov]

suggest to connect camera module and then check CSI_MCLK. 

Alternatively you can try to configure it in uboot, as in above example.

Best regards
igor

[umit_kayacik]

Hi Igor,

Now i can see the 27mhz clock on the pin but clock is getting down when kernel started. 

I guess one of the driver resets the CSI MCLK. This is base kernel code there is no update or any module on that. 

How can i fix this? 

Cheers

[igorpadykov]

Hi Umit

suggest to connect camera module and then check CSI_MCLK. 

Best regards
igor