i.MX8mm 2M+ baudrate broken on UART0 with kernel 5.15.32 (works on 5.4)

[Harvie]

Hello,

i have troubles with high speed communication on UART0 since upgrading to kernel 5.15.32.

115200 and 1M baud seems to work ok. But i need 3M baud communication and it seems unreliable.

Previously used kernel 5.4 provided by NXP and everything worked very nicely without single issue.

I have DMA enabled in device tree and SDMA firmware in place:

eec59b6ed17cda161c5ea4b8ab965338 /lib/firmware/imx/sdma/sdma-imx7d.bin

Even tried to disable DMA, but does not seem to help.

Any ideas what might be causing this? Thanks.

[Harvie]

I am including freescale/imx8mm.dtsi from linux-imx 5.15.32 and then applying following modifications to switch to 80MHz clock to achiveve 3M baudrate. BTW this seems to work in mainline kernel, but not on linux-imx:

&uart1 {

assigned-clocks = <&clk IMX8MM_CLK_UART1>;
assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>;

status = "okay";

}

[AldoG]

Hello,

Could you share the actual changes you have made to enable 3M baud rate?
Also, I believe that you're using NXP EVK and BSP, correct?

Best regards,
Aldo.