i.MX ProcessorsのトピックRe: IMX8MM How to modify SPI clock source?

IMX8MM How to modify SPI clock source?

Sarajia — Wed, 18 Aug 2021 23:38:22 GMT

Hi Sir，

Please tell me how to modify the SPI clock source. I now change it to 24Mhz， and the actual SPI rate is only (24 / (0 + 1) > > 0) more than 12Mhz.
Imx6u can reach 60Mhz
clocks = <&clk IMX8MM_ CLK_ ECSPI2_ ROOT>,
<&clk IMX8MM_ CLK_ ECSPI2_ ROOT>,
<&clk IMX8MM_ CLK_ ECSPI2_ SRC>,
<&clk IMX8MM_ CLK_ ECSPI2_ CG>,
<&clk IMX8MM_ CLK_ ECSPI2_ PRE_ DIV>,
<&clk IMX8MM_ CLK_ ECSPI2_ DIV>;
clock-names = "ipg", "per", "src", "cg", "pre_ div", "div";
I tried in DTS. These are 24Mhz

Pls show your hands on this issue.

Thanks a lot.

Re: IMX8MM How to modify SPI clock source?

igorpadykov — Thu, 19 Aug 2021 00:42:03 GMT

Hi Sara

one can look at below ecspi2 example

https://github.com/boundarydevices/linux-imx6/blob/boundary-imx_5.4.x_2.3.0/arch/arm64/boot/dts/freescale/imx8mm-nitrogen8mm.dts

pay attention to

assigned-clock-parents

assigned-clock-rates = <40000000>;
spi-max-frequency = <10000000>;

Clock sources can be found in clk driver

https://github.com/boundarydevices/linux-imx6/blob/boundary-imx_5.4.x_2.3.0/drivers/clk/imx/clk-imx8mm.c

Best regards
igor