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GPT capture sample on M4 seems to hang on Linux boot

Question asked by Gowri CP on Apr 18, 2019
Latest reply on Oct 16, 2019 by yingjin yan

Platform: iMX8MQ EVK

Linux kernel: 4.14.78

Yocto: imx-linux-sumo  4.14.98-1.0.0 GA

 

I tried running the GPT capture sample in SDK 2.5.1 on the M4. I have an external signal connected to GPT1_CAPTURE1 via TP 803. This works just fine till Linux starts to boot. At some point during bootup, the GPT sample stops working. I have disabled sound card support entirely and notice that GPT1 is disabled in the device tree (<yocto_build_dir>/tmp/work-shared/imx8mqevk/kernel-source/arch/arm64/boot/dts/freescale/fsl-imx8mq.dtsi). Table 2-3 in the Linux reference manual states that iMX8M uses the System Counter Timer instead of GPT. Given what I know, I do not understand if there is a resource conflict between Linux and M4, or in general, why this sample would stop working when Linux starts to come up.

 

Also, it looks like for this platform, GPT1 is the only timer with a pin out for capture channels so I can't use any other timers on the M4. Any help would be greatly appreciated!

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