iMX8M Mini CLK Generator Clocking Issue

[zhirongyang]

The PCIe clock generator 9FGV0241 takes its input from another clock source (25Mhz). This is different from the iMX8M Mini's main clock (24Mhz). Will want to check with you on some potential clocking issue.

As the clock source is different, it seems that it is like an asynchronous configuration rather than the synchronous. Does PCIe operation always operate in asynchronous mode?

The reason we want to know by having an independent clock generator (rather than using the clock from the IMX8M mini), how is the synchronization between the IMX8M mini and 9FGV0241AKLF going to be worked out?

Or simply that we do not care about the clock synchronization between these 2 clock source as PCIe operation is always independent.

The PCIe clk generator is I2C control. It seems that this required a driver and it can be setup to perform the necessary clock transcation.

[weidong_sun]

Hello Zhirong,

The following are suggestions for you:
1. For PCIe clock generator, please refer to the base board of I.MX8MQ-EVK!
2. Regarding the issue of synchronization, you don't need to care about 25MHZ and 24MHZ, but about the 2 PCIe REF CLK outputs of the clock generator, which must be synchronized. That is, the REF CLOCK of the CPU PCIE and PCIE device must be synchronized.
3. You don't need to care about the I2C driver of 9FGV0241AKLF, because BSP will support it. If you open the linux device tree,  you will find that this driver is not loaded in the I2C2 node, indicating that the default configuration of the clock generator can meet the requirements and does not need to be set.
4. The clock generator of the base board can also use PI6CFGL201BZDIEX, which is a product of Diodes. You can find it on www.diodes.com.

Hope above information is helpful to you.

Have a nice day!

B.R,

weidong