Verdin dahlia IMX8MP kernel oops when trying to write to /dev/ttymxc0

Latest Dahila with latest Verdin SOM IMX8 MP
[ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd034]
[ 0.000000] Linux version 5.15.77-6.4.0-devel+git.ddc6ca4d76ea (oe-user@oe-host) (aarch64-tdx-linux-gcc (GCC) 11.4.0, GNU ld (GNU Binutils) 2.38.20220708) #1 SMP PREEMPT Thu Jun 29 10:14:22 UTC 2023
[ 0.000000] Machine model: Toradex Verdin iMX8M Plus on Verdin Development Board

Using yocto.

I am seeing a kernel oops when trying to write to /dev/ttymxc0

[ 1889.188820] Call trace:
[ 1889.191267] sdma_transfer_init+0x128/0x32c [imx_sdma]
[ 1889.196419] sdma_prep_slave_sg+0x7c/0x324 [imx_sdma]
[ 1889.201482] imx_uart_dma_tx+0xdc/0x260
[ 1889.205324] imx_uart_start_tx+0x10c/0x1f4
[ 1889.209424] __uart_start.isra.0+0x3c/0x4c
[ 1889.213528] uart_write+0xfc/0x86c
[ 1889.216933] do_output_char+0x178/0x1a4
[ 1889.220774] n_tty_write+0x168/0x46c
[ 1889.224354] file_tty_write.constprop.0+0x130/0x294
[ 1889.229236] tty_write+0x14/0x20
[ 1889.232467] new_sync_write+0xe8/0x184
[ 1889.236221] vfs_write+0x22c/0x290
[ 1889.239626] ksys_write+0x68/0xf4
[ 1889.242948] __arm64_sys_write+0x1c/0x2c
[ 1889.246875] invoke_syscall+0x48/0x114
[ 1889.250630] el0_svc_common.constprop.0+0xd4/0xfc
[ 1889.255341] do_el0_svc+0x28/0x90
[ 1889.258660] el0_svc+0x28/0x80
[ 1889.261723] el0t_64_sync_handler+0xa4/0x130
[ 1889.265998] el0t_64_sync+0x1a0/0x1a4
[ 1889.269669] Code: b9002740 52800400 531b6ac2 72a03060 (b9000320)
[ 1889.275765] —[ end trace ca83092c4c6cc505 ]—


Is your OS based on our reference image? The PREMPT_RT BSPs and images are released in an experimental state. So there is the possibility this has not been fully tested/functional.

It looks like you are trying to use the sdma for uart. Can you provide a bit more information your situation?


I am using the yocto downloaded from your site for verdin/dahila.
The yocto does not appear to create or install the sdma-imx7d.bin into /lib/firmware/imx/sdma/ or create that directory path.

Hey @kuatwal,

For the downloaded version, did you use the prebuilt image from our easy installer or build the image with the patch configured in?

Can you describe your application aspect a bit more? Are you intending to use UART with dma?

Does the OS operate as intended without your read/writing aspect?


Hey @kuatwal,

Any updates on this topic?


I downloaded the yocto from your site and build it. I did not use a prebuilt image.