topic Re: i.MX8 Change USB OTG Clock in i.MX Processors

i.MX8 Change USB OTG Clock

cdgarren — Thu, 25 Mar 2021 19:17:28 GMT

I'm trying to change the USB OTG peripheral clock to AUDIO_PLL2 in order to have the same clock source for USB OTG and some SAI peripherals. I tried to make this change in my device tree:

&usbotg1 { dr_mode = "peripheral"; picophy,pre-emp-curr-control = <3>; picophy,dc-vol-level-adjust = <7>; + assigned-clock-parents = <&clk IMX8MM_AUDIO_PLL2_OUT>; status = "okay"; };

But my kernel no longer finishes booting. How can I accomplish this?

Re: i.MX8 Change USB OTG Clock

AldoG — Mon, 29 Mar 2021 23:45:40 GMT

Hello,

May I ask which kernel version are you planning to use?
Also, could you tell me the device you're using for your test?

Thank you,
Best regards,
Aldo.

Re: i.MX8 Change USB OTG Clock

cdgarren — Tue, 30 Mar 2021 00:05:25 GMT

This is with kernel version 5.4.47 and is running on an i.MX8MM

Re: i.MX8 Change USB OTG Clock

AldoG — Thu, 01 Apr 2021 00:29:24 GMT

Hello,

Got it, you'll need to change the parent clock not in the USB node but in the USB phy.

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mm.dtsi?h=imx_5.4.47_2.2.0#n380

Please try the following:

usbphynop1: usbphynop1 {
                compatible = "usb-nop-xceiv";
                clocks = <&clk IMX8MM_CLK_USB_PHY_REF>;
                assigned-clocks = <&clk IMX8MM_CLK_USB_PHY_REF>;
- assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_100M>;
+ assigned-clock-parents = <&clk IMX8MM_AUDIO_PLL2_OUT>;
                clock-names = "main_clk";
        };

Best regards,
Aldo.