iMX8MM Kernel 5.4.85: Unable to get /dev/rpmsg node

[harsh1621]

I am attempting to get the rpmsg node online on iMX8MM var-som board running Linux Kernel 5.4.85. I am following the dts here: https://github.com/varigit/linux-imx/blob/5.4-2.1.x-imx_var01/arch/arm64/boot/dts/freescale/imx8mm-v... 

However, I get the following Kernel Logs on boot:

[ 0.209340] imx rpmsg driver is registered.
[ 1.073890] imx-rpmsg 40000000.rpmsg: assigned reserved memory node vdevbuffer@0x40400000
[ 1.085409] virtio_rpmsg_bus: probe of virtio0 failed with error -12

I have all the necessary kernel configs enabled, so doesn't look like a case of missing kernel module. How should I proceed to debug further from the above error message.

Edit 1: If I define a different reserved memory which is not a "shared-dma-pool", I am able to get the rpmsg node online with the following success messages:

[ 0.209390] imx rpmsg driver is registered.
[ 0.773516] virtio_rpmsg_bus virtio0: rpmsg host is online
[ 0.773807] virtio_rpmsg_bus virtio0: creating channel rpmsg-openamp-demo-channel addr 0x1e

However, why would a reserved memory node with "shared-dma-pool" attribute not work?

[igorpadykov]

Hi Harshvardhan

reason may be that in imx8mm-var-som-symphony-m4.dtsi
&rpmsg{..
status = "disabled";

one can find appropriate dts file for that board where it is enabled as in example below

https://github.com/varigit/linux-imx/blob/imx_4.19.35_1.1.0_var01/arch/arm64/boot/dts/freescale/fsl-...

Best regards
igor

[harsh1621]

@igorpadykov Hi, actually I have set the status to "okay" and yet I'm facing this problem. Any other suggestions I should look into?

[igorpadykov]

iMX8MM var-som board is third party board supported by variscite, may be suggested to post issue

on vendor forum:   https://variwiki.com/index.php?title=Main_Page

Best regards
igor