LPUART3 support in verdin imx95

junaidh12 — Thu, 28 Aug 2025 06:34:36 GMT

Hi all,

I am working on an verdin i.MX95 19x19 EVK and trying to enable LPUART3 in the device tree. After my changes, the kernel panics during boot.

Device tree changes

diff --git a/arch/arm64/boot/dts/freescale/imx95-19x19-evk.dts b/arch/arm64/boot/dts/freescale/imx95-19x19-evk.dts index 4aa2d000df8b..55d660ce38aa 100644 --- a/arch/arm64/boot/dts/freescale/imx95-19x19-evk.dts +++ b/arch/arm64/boot/dts/freescale/imx95-19x19-evk.dts @@ -570,6 +570,12 @@ &lpuart1 { status = "okay"; }; +&lpuart3 { + pinctrl-names = "default"; + pinctrl-0 = <&pinctrl_uart3>; + status = "okay"; +}; + &lpuart5 { /* BT */ pinctrl-names = "default"; @@ -980,6 +986,13 @@ IMX95_PAD_UART1_TXD__AONMIX_TOP_LPUART1_TX 0x31e >; }; + pinctrl_uart3: uart3grp { + fsl,pins = < + IMX95_PAD_ENET1_RD0__LPUART3_RX 0x31e + IMX95_PAD_ENET1_TD0__LPUART3_TX 0x31e + >; + }; + pinctrl_uart5: uart5grp { fsl,pins = < IMX95_PAD_DAP_TDO_TRACESWO__LPUART5_TX 0x31e

Boot Logs

[ 2.234704] /soc/bus@42000000/i2c@426d0000/tcpc@52/connector: Fixed dependency cycle(s) with /soc/phy@4c1f0040 [ 2.244734] i2c i2c-6: LPI2C adapter registered [ 2.250234] adp5585 1-0034: error -EIO: Failed to read device ID [ 2.256064] adp5585 1-0034: probe with driver adp5585 failed with error -5 [ 2.262925] i2c i2c-1: LPI2C adapter registered [ 2.268342] imx8mq-usb-phy 4c1f0040.phy: supply vbus not found, using dummy regulator [ 2.281775] /soc/bridge@4b0d0000/channel@0: Fixed dependency cycle(s) with /soc/syscon@4b010000/bridge@8 [ 2.291122] /soc/syscon@4b0c0000/ldb@4/channel@0: Fixed dependency cycle(s) with /soc/syscon@4b010000/bridge@8 [ 2.301094] /soc/syscon@4b010000/bridge@8: Fixed dependency cycle(s) with /soc/syscon@4b0c0000/ldb@4/channel@0 [ 2.310967] /soc/syscon@4b010000/bridge@8: Fixed dependency cycle(s) with /soc/bridge@4b0d0000/channel@0 [ 2.321873] /soc/syscon@4b0c0000/ldb@4/channel@0: Fixed dependency cycle(s) with /lvds0_panel [ 2.330249] /soc/syscon@4b0c0000/ldb@4/channel@0: Fixed dependency cycle(s) with /soc/syscon@4b010000/bridge@8 [ 2.342922] scmi-pinctrl-imx scmi_dev.8: Error set config -13 [ 2.348464] scmi-pinctrl-imx scmi_dev.8: pin_config_set op failed for pin 56 [ 2.355438] fsl-lpuart 42570000.serial: Error applying setting, reverse things back [ 2.363245] Internal error: synchronous external abort: 0000000096000010 [#1] PREEMPT SMP [ 2.371199] Modules linked in: [ 2.374234] CPU: 0 UID: 0 PID: 60 Comm: kworker/u24:3 Not tainted 6.12.20-lts-next-gdfaf2136deb2-dirty #1 [ 2.383764] Hardware name: NXP i.MX95 19X19 board (DT) [ 2.388879] Workqueue: events_unbound deferred_probe_work_func [ 2.394685] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 2.401611] pc : lpuart_probe+0x55c/0x630 [ 2.405598] lr : lpuart_probe+0x33c/0x630 [ 2.409591] sp : ffff800083083b20 [ 2.412884] x29: ffff800083083b30 x28: 0000000000000000 x27: 0000000000000000 [ 2.419991] x26: ffff000080b4c240 x25: 0000000000000000 x24: ffff800080876bf0 [ 2.427091] x23: ffff8000822d9bc8 x22: ffff000080208410 x21: ffff000080208400 [ 2.434198] x20: 0000000000000000 x19: ffff00008177a880 x18: ffffffffffffffff [ 2.441304] x17: ffff0000815ee000 x16: ffff0000815ede00 x15: 0000000000000002 [ 2.448411] x14: ffffffffffffffff x13: ffff0000807bc580 x12: 0000000000000001 [ 2.455518] x11: 000000008bb15db4 x10: 0000000000000a90 x9 : ffff800083083830 [ 2.462624] x8 : ffff0003fdf58c80 x7 : 1000000000000104 x6 : 0000000000000002 [ 2.469731] x5 : 1000000000000004 x4 : ffff0000807bc500 x3 : 0000000000000000 [ 2.476838] x2 : ffff800082400278 x1 : 0000000000000003 x0 : ffff8000825c3018 [ 2.483951] Call trace: [ 2.486378] lpuart_probe+0x55c/0x630 [ 2.490018] platform_probe+0x68/0xc8 [ 2.493651] really_probe+0xbc/0x29c [ 2.497205] __driver_probe_device+0x78/0x12c [ 2.501538] driver_probe_device+0x3c/0x15c [ 2.505698] __device_attach_driver+0xb8/0x134 [ 2.510118] bus_for_each_drv+0x88/0xe8 [ 2.513931] __device_attach+0xa0/0x190 [ 2.517744] device_initial_probe+0x14/0x20 [ 2.521904] bus_probe_device+0xac/0xb0 [ 2.525718] deferred_probe_work_func+0x80/0xb8 [ 2.530224] process_one_work+0x148/0x28c [ 2.534211] worker_thread+0x2c8/0x3d0 [ 2.537938] kthread+0x110/0x114 [ 2.541144] ret_from_fork+0x10/0x20 [ 2.544707] Code: f9411260 97fbe006 17ffff17 91002000 (b940001a) [ 2.550772] ---[ end trace 0000000000000000 ]---

Question

Are ENET1_RD0 and ENET1_TD0 the correct pads for LPUART3 RX/TX on this board?
Do I need to adjust SCMI/firmware ownership of these pins for Linux to use them?
Does anyone have a known-good DTS snippet for LPUART3 on the i.MX95 EVK?

Thanks!

Re: LPUART3 support in verdin imx95

Zhiming_Liu — Thu, 28 Aug 2025 07:19:47 GMT

Hi,

The LPUART3 is assigned for M7 in scmi. Need to modify https://github.com/nxp-imx/imx-sm/blob/master/configs/mx95evk.cfg#L373 , remove this line from M7 resources.

LPUART3 OWNER, test

And try to add below line in A55 resources.

PERLPI_LPUART3 ALL

Best Regards,
Zhiming

Re: LPUART3 support in verdin imx95

junaidh12 — Sun, 07 Sep 2025 14:57:40 GMT

Thank you @Zhiming_Liu; The solution you provided worked. I did the following changes in the imx-system-manager code related to lpuart3 along with my device tree changes and build a new yocto image. ttyLP2 was in the /dev/ and I also used it in my application and was also running successfully.

Changes in imx-system-manager code:

--- a/configs/mx95evk.cfg +++ b/configs/mx95evk.cfg @@ -370,7 +370,6 @@ LPIT1 OWNER LPTMR1 OWNER LPTMR2 OWNER LPTPM1 OWNER -LPUART3 OWNER, test MSGINTR1 OWNER MSGINTR2 OWNER MU5_A OWNER @@ -477,6 +476,7 @@ PERLPI_GPIO3 ALL PERLPI_GPIO4 ALL PERLPI_GPIO5 ALL PERLPI_LPUART1 ALL +PERLPI_LPUART3 ALL PERLPI_LPUART4 ALL PERLPI_LPUART5 ALL PERLPI_LPUART6 ALL @@ -760,6 +760,7 @@ LPTPM4 OWNER LPTPM5 OWNER LPTPM6 OWNER LPUART1 OWNER +LPUART3 OWNER LPUART4 OWNER LPUART5 OWNER LPUART6 OWNER

my /dev directory

root@imx95:~# ls -al /dev/ttyLP2 crw-rw---- 1 root dialout 241, 2 Sep 7 14:30 /dev/ttyLP2 root@imx95:~# dmesg | grep ttyLP2 [ 2.426195] 42570000.serial: ttyLP2 at MMIO 0x42570010 (irq = 141, base_baud = 1500000) is a FSL_LPUART

i.MX Processors中的主题 LPUART3 support in verdin imx95

LPUART3 support in verdin imx95

Re: LPUART3 support in verdin imx95

Re: LPUART3 support in verdin imx95