How do we use iMX8QM's uart to recieve GNSS module data

[Tamako]

Now  I have an iMX8QM ,I want to use it to recieve GNSS module ,but I can't test the uart of iMX8QM ,beacuse it looks like the iMX8QM just only have 5 uarts ,LP1 and LP2 is using to debug the core of A72 and A53，and another 1 is using to bluetooth module ,the last of 2 is connecting to the 2 M4 cores,I want to konw how I use the GNSS module connect to uart to revieve data?

[joanxie]

you can choose one uart if you don't use it for other function, to enable it in the dts file you use

[EmptyObject_]

 I can not use lpuart3/lpuart4,how do i use this two lpuart ?For me ,l just can use this two lpuart ,and I have enabled the two  in the dtb file,but I can not use.

[joanxie]

besides this, pls don't forget add this

--- a/arch/arm64/boot/dts/freescale/imx8qm-ss-dma.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8qm-ss-dma.dtsi
@@ -146,6 +146,8 @@

&lpuart3 {
compatible = "fsl,imx8qm-lpuart", "fsl,imx8qxp-lpuart";
+ dmas = <&edma2 13 0 0>,
+ <&edma2 12 0 1>;
};

[EmptyObject_]

I got a new question about lpuart now ,I did the loopback test,I send a string once ,but the rx

recieved three times ,and I checked all the lpuart ,there are all the same situation.Do you know how to resolve it?

[joanxie]

I already found you created a new case for this issue, pls follow that case for the new issue

[joanxie]

I don't know what bsp you use, as I mentioned before, pls check the dts file you use, then enable it in the dts, for example

https://github.com/nxp-imx/linux-imx/blob/lf-5.15.y/arch/arm64/boot/dts/freescale/imx8qm-mek.dts

you can find lpuart3 is disabled, you need set it to OK if you need to use it, this is just for reference, you can set by yourself on your own bsp