Failed to use uart3 in i.mx8mp

[dskim2]

After building i.mx8mp as Yocto core-image-base, downloading it to the target board and opening it to use uart3, the following error occurred.
how can i solve it?

I already tried to use sdma as a module, but it didn't work.

imx-uart 30880000.serial: We cannot prepare for the RX slave dma!

WOBD communication....open_port: [   39.025350] Unable to handle kernel NULL poi

nter dereference at virtual address 0000000000000000

/dev/ttymxc2 [4099] =>[  O K 3

.036511] Mem abort info:

[   39.041556]   ESR = 0x96000044

[   39.044610]   EC = 0x25: DABT (current EL), IL = 32 bits

[   39.049919]   SET = 0, FnV = 0

[   39.052972]   EA = 0, S1PTW = 0

[   39.056110] Data abort info:

[   39.058988]   ISV = 0, ISS = 0x00000044

[   39.062823]   CM = 0, WnR = 1

[   39.065790] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000107947000

[   39.072228] [0000000000000000] pgd=0000000000000000, p4d=0000000000000000

[   39.079019] Internal error: Oops: 96000044 [#1] PREEMPT SMP

[   39.084590] Modules linked in: rpcsec_gss_krb5 fsl_jr_uio caam_jr caamkeyblob

_desc caamhash_desc caamalg_desc crypto_engine rng_core authenc libdes crct10dif

_ce imx8_media_dev(C) caam flexcan can_dev secvio error fuse

[   39.103913] CPU: 1 PID: 481 Comm: serial_test Tainted: G         C        5.1

0.72-lts-5.10.y+ga68e31b63f86 #1

[   39.113825] Hardware name: NXP i.MX8MPlus MicroVision EVK board (DT)

[   39.120178] pstate: 80000085 (Nzcv daIf -PAN -UAO -TCO BTYPE=--)

[   39.126188] pc : sdma_transfer_init+0x130/0x260

[   39.130717] lr : sdma_transfer_init+0xc0/0x260

[   39.135158] sp : ffff80001245ba50

[   39.138471] x29: ffff80001245ba50 x28: ffff0000c0c588c8

[   39.143784] x27: ffff0000c6607807 x26: ffff0000c0c5c6a8

[   39.149097] x25: 0000000000000080 x24: 0000000000000000

[   39.154409] x23: 0000000000000080 x22: ffff0000c0c58080

[   39.159722] x21: ffff800011d6d200 x20: ffff0000c643eb00

[   39.165034] x19: ffff0000c0c588c8 x18: 0000000000000000

[   39.170347] x17: 0000000000000000 x16: 0000000000000000

[   39.175660] x15: 001fffffffffffff x14: 0000000000180000

[   39.180972] x13: 0000000000008000 x12: 0000000000001000

[   39.186285] x11: 00000000ffffffff x10: ffff80001245ba70

[   39.191597] x9 : 0000000000000000 x8 : ffff800012088000

[   39.196910] x7 : 0000000000000000 x6 : 000000000000003f

[   39.202222] x5 : 0000000000000040 x4 : 0000000000000000

[   39.207534] x3 : ffff0000c0c5c6a8 x2 : 0000000000000001

[   39.212847] x1 : 00000000000002ed x0 : 0000000001830020

[   39.218159] Call trace:

[   39.220606]  sdma_transfer_init+0x130/0x260

[   39.224789]  sdma_prep_slave_sg+0x6c/0x280

[   39.228886]  imx_uart_dma_tx+0xdc/0x230

[   39.232721]  imx_uart_start_tx+0x10c/0x230

[   39.236818]  __uart_start.isra.0+0x3c/0x50

[   39.240914]  uart_write+0x100/0x890

[   39.244403]  n_tty_write+0x2bc/0x46c

[   39.247979]  file_tty_write.constprop.0+0x138/0x290

[   39.252855]  tty_write+0x14/0x20

[   39.256084]  new_sync_write+0xe8/0x180

[   39.259832]  vfs_write+0x244/0x2a4

[   39.263233]  ksys_write+0x6c/0x100

[   39.266633]  __arm64_sys_write+0x20/0x30

[   39.270557]  el0_svc_common.constprop.0+0x78/0x1c4

[   39.275344]  do_el0_svc+0x24/0x8c

[   39.278660]  el0_svc+0x14/0x20

[   39.281713]  el0_sync_handler+0x1a4/0x1b0

[   39.285722]  el0_sync+0x180/0x1c0

[   39.289039] Code: b90026a0 52800400 531b6af7 72a03060 (b9000300)

[   39.295131] ---[ end trace 6eb135a2e9b977ca ]---

[   39.299749] note: serial_test[481] exited with preempt_count 2

Broadcast message from systemd-journald@imx8mp-lpddr4-evk (Wed 2021-03-24 10:25:

54 UTC):

kernel[432]: [   39.079019] Internal error: Oops: 96000044 [#1] PREEMPT SMP

Broadcast message from systemd-journald@imx8mp-lpddr4-evk (Wed 2021-03-24 10:25:

54 UTC):

kernel[432]: [   39.289039] Code: b90026a0 52800400 531b6af7 72a03060 (b9000300)

[cassiopeia-choi]

I applied this too, but there is still an error.

CORE_IMAGE_EXTRA_INSTALL += " firmwared"

The following is my detailed progress list.

1. [ imx8mp evk board ]

2. [ yocto imx-linux-hardknott branch ]

3. [ imx-5.10.72-2.2.2.xml ]

4. DISTRO=fsl-imx-wayland MACHINE=imx8mpevk source imx-setup-release.sh -b build

5. bitbake core-image-minimal

6. CORE_IMAGE_EXTRA_INSTALL += " firmwared"

7. disable kernel sdma config  #CONFIG_IMX_SDMA=y

but, UART3 can't working....

[dskim2]

Try enable SDMA

[cassiopeia-choi]

 I have already tred it... ;;;

[dskim2 · Accepted solution]

I solved the problem in the following way.
Add the below to the conf/local.conf file

CORE_IMAGE_EXTRA_INSTALL += " firmwared"

[cassiopeia-choi]

I use [ imx8mp evk board ] , [ yocto imx-linux-hardknott branch ] [ imx-5.10.72-2.2.2.xml ]

[cassiopeia-choi]

The same problem arises for me, too. So I can't proceed with the work at all.