# Kernel panic and Bluetooth degradation on ConnectCore MP25 (DEY Yocto) **URL:** \ **Category:** Linux\ **Tags:** kernel, embedded-linux, stm32, hardware\ **Created:** [March 23, 2026, 11:44am UTC](https://forums.digi.com/t/kernel-panic-and-bluetooth-degradation-on-connectcore-mp25-dey-yocto/38294 "2026-03-23T11:44:44Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![ASN](https://avatars.discourse-cdn.com/v4/letter/a/c0e974/32.png) [@ASN](https://forums.digi.com/u/ASN)\ **Post date:** [March 23, 2026, 11:44am UTC](https://forums.digi.com/t/kernel-panic-and-bluetooth-degradation-on-connectcore-mp25-dey-yocto/38294/1 "2026-03-23T11:44:44Z")
Hello, I am working with the Digi Embedded Yocto distribution on a ConnectCore MP25 platform, following the official tutorial: [Install Digi Embedded Yocto | ConnectCore MP25](https://docs.digi.com/resources/documentation/digidocs/embedded/dey/5.0/ccmp25/yocto-install-dey_t.html) The system is based on the **`dey-image-webkit`** image. Observed Behavior - Initially, Bluetooth communication works correctly. - After a few minutes: - Eventually: Here’s the complete kernel log : `[690.252572] Unable to handle kernel paging request at virtual address dead000000000108` `[690.254944] Mem abort info:` `[690.257770] ESR = 0x0000000096000044` `[690.261500] EC = 0x25: DABT (current EL), IL = 32 bits` `[690.266838] SET = 0, FnV = 0` `[690.269962] EA = 0, S1PTW = 0` `[690.273085] FSC = 0x04: level 0 translation fault` `[690.278016] Data abort info:` `[690.280835] ISV = 0, ISS = 0x00000044, ISS2 = 0x00000000` `[690.286368] CM = 0, WnR = 1, TnD = 0, TagAccess = 0` `[690.291500] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0` `[690.296834] [dead000000000108] address between user and kernel address ranges` `[690.303976] Internal error: Oops: 0000000096000044 [` #1`] PREEMPT SMP` `[690.310317] Modules linked in: hci_uart btbcm brcmfmac_cyw brcmfmac brcmutil galcore(O) stm32_dcmipp stm32_csi stm32_lptimer stm32_crc32 stm32_cryp crypto_engine spi_stm32 optee_rng nfnetlink` `[690.327469] CPU: 0 PID: 10 Comm: kworker/0:1 Tainted: G O 6.6.78-dey-gf582bf40eaa4-dirty ` #1 `[690.337328] Hardware name: Digi International ConnectCore MP25 Development Kit (DT)` `[690.344973] Workqueue: pm pm_runtime_work` `[690.349017] pstate: 200000c5 (nzCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=–)` `[690.356063] pc : vchan_tx_submit+0x58/0x8c` `[690.360201] lr : vchan_tx_submit+0x28/0x8c` `[690.364235] sp : ffff800081b1bba0` `[690.367657] x29: ffff800081b1bba0 x28: 0000000000000000 x27: 0000000000000000` `[690.374809] x26: ffff000005ed34f4 x25: 0000000000000000 x24: 0000000000000000` `[690.381960] x23: 0000000000000000 x22: ffff000006abfd80 x21: ffff000005ea46a0` `[690.389212] x20: 00000000000001ba x19: ffff0000123880c0 x18: 0000000000000000` `[690.396363] x17: 0000000000000000 x16: 0000000000000000 x15: 0000376c62d55142` `[690.403515] x14: ffff000005edb010 x13: 0000000000000000 x12: 0000000000000001` `[690.410766] x11: 0000000000000000 x10: 0000000000000001 x9 : 0000000000000002` `[690.417917] x8 : ffff000005ea4748 x7 : 0000000000084000 x6 : 0000000000000800` `[690.425068] x5 : ffff000005ea4758 x4 : dead000000000100 x3 : dead000000000122` `[690.432320] x2 : ffff000012388138 x1 : 0000000000000000 x0 : ffff000005ea4740` `[690.439473] Call trace:` `[690.441893] vchan_tx_submit+0x58/0x8c` `[690.445727] stm32_usart_rx_dma_start_or_resume+0xd8/0x234` `[690.451271] stm32_usart_runtime_resume+0x78/0xe8` `[690.455908] pm_generic_runtime_resume+0x2c/0x44` `[690.460643] __genpd_runtime_resume+0x30/0x80` `[690.464976] genpd_runtime_resume+0x110/0x244` `[690.469410] __rpm_callback+0x48/0x1d8` `[690.473142] rpm_callback+0x6c/0x78` `[690.476671] rpm_resume+0x490/0x6b4` `[690.480102] pm_runtime_work+0x84/0xc8` `[690.483933] process_one_work+0x144/0x29c` `[690.487970] worker_thread+0x31c/0x434` `[690.491703] kthread+0x110/0x114` `[690.494934] ret_from_fork+0x10/0x20` `[690.498571] Code: 1a9fc694 b9001074 b8078454 a9478e64 (f9000483)` `[690.504708] —[end trace 0000000000000000]—` `[690.509337] note: kworker/0:1[10] exited with irqs disabled` `[690.515075] note: kworker/0:1[10] exited with preempt_count 1` `[690.515217] Bluetooth: hci0: Frame reassembly failed (-90)` `[703.508334] Bluetooth: hci0: command tx timeout` `[718.516874] Bluetooth: hci0: command tx timeout` `[733.525017] Bluetooth: hci0: command tx timeout` `[748.533392] Bluetooth: hci0: command tx timeout` `[763.545749] Bluetooth: hci0: command tx timeout` `[778.551855] Bluetooth: hci0: command tx timeout` `[793.559498] Bluetooth: hci0: command tx timeout` `[808.567183] Bluetooth: hci0: command tx timeout` `[810.743145] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[810.743415] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 1` `[813.302925] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[813.303181] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 2` `[815.863251] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[815.863501] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 3` `[818.423315] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[820.983369] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[820.983624] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 1` `[823.543357] Bluetooth: hci0: command tx timeout` `[823.543352] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[823.548152] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 2` `[826.103381] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[826.103636] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 3` `[828.663438] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[828.663700] ieee80211 phy0: brcmf_run_escan: error (-110)` `[828.669187] ieee80211 phy0: brcmf_cfg80211_scan: scan error (-110)` `[838.551836] Bluetooth: hci0: command tx timeout` `[853.559957] Bluetooth: hci0: command tx timeout` `[868.568308] Bluetooth: hci0: command tx timeout` `[883.576913] Bluetooth: hci0: command tx timeout` `[898.589453] Bluetooth: hci0: command tx timeout` `[913.593457] Bluetooth: hci0: command tx timeout` `[928.601982] Bluetooth: hci0: command tx timeout` `[931.577927] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[931.578177] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 1` `[934.138033] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[934.138287] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 2` `[936.698196] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[936.698459] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 3` `[939.257954] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[941.818288] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[941.818541] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 1` `[943.610242] Bluetooth: hci0: command tx timeout` `[944.378260] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[944.378513] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 2` `[946.938330] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[946.938584] brcmfmac: brcmf_fil_cmd_data: cmd error -110, resend cmd count 3` `[949.498472] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout` `[949.498733] ieee80211 phy0: brcmf_run_escan: error (-110)` `[949.504221] ieee80211 phy0: brcmf_cfg80211_scan: scan error (-110)` Questions - Is this a known issue with the DEY 6.6.78 kernel or ConnectCore MP25 platform? - Are there patches available for: - Would disabling runtime power management for the UART or Bluetooth device be a valid workaround? ### Technical Context - Hardware: ConnectCore MP25 Development Kit - Kernel: `6.6.78-dey` Best Regards, ASN ---
**Author:** ![abuzarra](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/abuzarra/32/9793_2.png) [@abuzarra](https://forums.digi.com/u/abuzarra)\ **Post date:** [April 8, 2026, 7:28pm UTC](https://forums.digi.com/t/kernel-panic-and-bluetooth-degradation-on-connectcore-mp25-dey-yocto/38294/2 "2026-04-08T19:28:42Z")
Hi, This issue is currently under investigation. We found that reverting the following commit: [https://github.com/digi-embedded/linux/commit/83771e186d2abeccc38b0a5e6841b068499622ca](https://github.com/digi-embedded/linux/commit/83771e186d2abeccc38b0a5e6841b068499622ca) and disabling DMA support on the Bluetooth UART makes the issue much harder to reproduce. However, we are working on an additional fix related to runtime PM support in the `stm32-usart` driver. We hope to finalize the investigation and provide a proper fix soon. Best regards, ---
**Author:** ![ASN](https://avatars.discourse-cdn.com/v4/letter/a/c0e974/32.png) [@ASN](https://forums.digi.com/u/ASN)\ **Post date:** [April 10, 2026, 1:10pm UTC](https://forums.digi.com/t/kernel-panic-and-bluetooth-degradation-on-connectcore-mp25-dey-yocto/38294/3 "2026-04-10T13:10:25Z")
Hi, Thank you for the update. I will try to revert the mentioned commit and disable DMA support on the Bluetooth UART to see if it improves the situation on my side. Regarding your findings, would you recommend a specific way to disable DMA for the Bluetooth UART (e.g. via device tree changes), or should I simply remove the DMA configuration entries? I will also run additional tests to check whether the issue becomes harder to reproduce and will report back with my observations. Please let me know if you would like me to test any specific patches or configurations related to the runtime PM changes in the stm32-usart driver. Thanks for your reply! Best regards, ASN ---
**Author:** ![abuzarra](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/abuzarra/32/9793_2.png) [@abuzarra](https://forums.digi.com/u/abuzarra)\ **Post date:** [April 13, 2026, 8:37am UTC](https://forums.digi.com/t/kernel-panic-and-bluetooth-degradation-on-connectcore-mp25-dey-yocto/38294/4 "2026-04-13T08:37:40Z")
Hi, To disable UART DMA you need to remove the DMA properties from the DT overlay, for example: ```auto --- a/arch/arm64/boot/dts/digi/ccmp25_bt.dtso +++ b/arch/arm64/boot/dts/digi/ccmp25_bt.dtso @@ -43,6 +43,9 @@ __overlay__ { pinctrl-2 = <&ccmp25_usart1_sleep_pins>; uart-has-rtscts; status = "okay"; + /* Remove DMA */ + /delete-property/dmas; + /delete-property/dma-names; ``` We are working together with ST to identify and fix the root cause of the issue, and we will provide a proper fix as soon as possible. Best regards, Arturo. ---
**Author:** ![ASN](https://avatars.discourse-cdn.com/v4/letter/a/c0e974/32.png) [@ASN](https://forums.digi.com/u/ASN)\ **Post date:** [May 7, 2026, 10:26am UTC](https://forums.digi.com/t/kernel-panic-and-bluetooth-degradation-on-connectcore-mp25-dey-yocto/38294/5 "2026-05-07T10:26:51Z")
Hi, Thank you for your guidance. I applied both changes (kernel modification + reverting the mentioned commit), and I can see a clear improvement. The kernel panic that occurred after a few minutes of BLE traffic is no longer happening! After several hours of testing, I may still encounter occasional Bluetooth errors: ![image](https://us1.discourse-cdn.com/flex016/uploads/digi/original/2X/0/0be05efb08016fd9554ef4d61157ac2acaab17b0.jpeg) However, the occurrence is now significantly lower compared to before applying the patches. Thanks a lot for your support — this already improves stability a lot on my side. Do you have any idea when the official fix might be available (e.g., in the coming months or rather next year)? Best regards, ASN ---
**Author:** ![abuzarra](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/abuzarra/32/9793_2.png) [@abuzarra](https://forums.digi.com/u/abuzarra)\ **Post date:** [May 12, 2026, 2:52pm UTC](https://forums.digi.com/t/kernel-panic-and-bluetooth-degradation-on-connectcore-mp25-dey-yocto/38294/6 "2026-05-12T14:52:09Z")
Hi, In the end, two changes are required: 1. Revert commit: `83771e186d2abeccc38b0a5e6841b068499622ca` 2. Protect `stm32_usart_rx_dma_start_or_resume()` with the UART port spin\_lock. Apply the following change: ```auto --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -2510,8 +2510,10 @@ static int __maybe_unused stm32_usart_serial_en_wakeup(struct uart_port *port, stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAT); if (stm32_port->rx_ch) { + spin_lock_irqsave(&port->lock, flags); stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAR); ret = stm32_usart_rx_dma_start_or_resume(port); + spin_unlock_irqrestore(&port->lock, flags); if (ret) return ret; } ``` With these two changes applied, the issue is resolved, and UART DMA can be re-enabled if needed. These patches will be included in the next DEY-5.0 release. Best regards, Arturo ---
**Author:** ![ASN](https://avatars.discourse-cdn.com/v4/letter/a/c0e974/32.png) [@ASN](https://forums.digi.com/u/ASN)\ **Post date:** [June 4, 2026, 12:25pm UTC](https://forums.digi.com/t/kernel-panic-and-bluetooth-degradation-on-connectcore-mp25-dey-yocto/38294/7 "2026-06-04T12:25:59Z")
Hi Arturo, Thank you for the detailed explanation and for confirming the final solution. And thanks a lot for your support and for clarifying that the fixes will be included in the next DEY‑5.0 release — that’s very helpful for our planning. Best regards, ASN ---
**Author:** ![abuzarra](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/abuzarra/32/9793_2.png) [@abuzarra](https://forums.digi.com/u/abuzarra)\ **Post date:** [June 4, 2026, 12:39pm UTC](https://forums.digi.com/t/kernel-panic-and-bluetooth-degradation-on-connectcore-mp25-dey-yocto/38294/8 "2026-06-04T12:39:25Z")
Hi, Digi Embedded Yocto **5.0-r4** (including all of these patches) is now available on GitHub. I hope this helps with your development. Best regards, Arturo. ---
**Author:** ![ASN](https://avatars.discourse-cdn.com/v4/letter/a/c0e974/32.png) [@ASN](https://forums.digi.com/u/ASN)\ **Post date:** [June 4, 2026, 12:54pm UTC](https://forums.digi.com/t/kernel-panic-and-bluetooth-degradation-on-connectcore-mp25-dey-yocto/38294/9 "2026-06-04T12:54:22Z")
Hi Arturo, Thank you for letting me know. That’s great news — I’ll switch to Digi Embedded Yocto 5.0‑r4 from GitHub and continue our development based on that release. Thanks again for your support! Best regards, ASN