How to get the clock value of rk3288-cru?

[李松錡]

Hi all,

 

I am new to kernel development, and I found an old ASUS tinkerboard. I want to give it a second life with some fun projects.

The project I am building is another IP KVM, so I bought an HDMI to CSI module. After tinkering around for a while, I found I supplied the wrong clock for that module:

 

[    8.469299] tc358743 2-000f: unsupported refclk rate: 50000000 Hz
[    8.483069] kernel BUG at drivers/media/i2c/tc358743.c:593!

 

I have no idea about the clock value to put in the dts file, so I just copied some values from the ASUS kernel source.

 

From the driver code drivers/media/i2c/tc358743.c, it shows that there are only 3 valid clocks:

 

switch (state->pdata.refclk_hz) {
case 26000000:
case 27000000:
case 42000000:
...
default:
    dev_err(dev, "unsupported refclk rate: %u Hz\n",
        state->pdata.refclk_hz);
...

 

However, the clock values used in the dts file are some pre-defined macros:

# dts configuration
clocks = <&cru SCLK_VIP_OUT>;
  
# include/dt-bindings/clock/rk3288-cru.h that contains the `SCLK_VIP_OUT`
...
#define SCLK_CRYPTO      125
#define SCLK_MIPIDSI_24M 126
#define SCLK_VIP_OUT     127
...
  

 

I wonder if some folks have experience with the clock setting and can help me pick the correct value. Thank you.