linux-stable.git/drivers/tty/serial, branch v6.3.7 Linux kernel stable tree serial: cpm_uart: Fix a COMPILE_TEST dependency 2023-06-09T08:48:23+00:00 Herve Codina herve.codina@bootlin.com 2023-05-23T08:59:02+00:00 1d50232736aaeacb17bb9b1191e8fe4384ab5b4f commit 7183c37fd53eee1e795206e625da12a5d7ec1e1a upstream. In a COMPILE_TEST configuration, the cpm_uart driver uses symbols from the cpm_uart_cpm2.c file. This file is compiled only when CONFIG_CPM2 is set. Without this dependency, the linker fails with some missing symbols for COMPILE_TEST configuration that needs SERIAL_CPM without enabling CPM2. This lead to: depends on CPM2 || CPM1 || (PPC32 && CPM2 && COMPILE_TEST) This dependency does not make sense anymore and can be simplified removing all the COMPILE_TEST part. Signed-off-by: Herve Codina <herve.codina@bootlin.com> Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/oe-kbuild-all/202305160221.9XgweObz-lkp@intel.com/ Fixes: e3e7b13bffae ("serial: allow COMPILE_TEST for some drivers") Cc: stable <stable@kernel.org> Link: https://lore.kernel.org/r/20230523085902.75837-3-herve.codina@bootlin.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 7183c37fd53eee1e795206e625da12a5d7ec1e1a upstream.

In a COMPILE_TEST configuration, the cpm_uart driver uses symbols from
the cpm_uart_cpm2.c file. This file is compiled only when CONFIG_CPM2 is
set.

Without this dependency, the linker fails with some missing symbols for
COMPILE_TEST configuration that needs SERIAL_CPM without enabling CPM2.

This lead to:
  depends on CPM2 || CPM1 || (PPC32 && CPM2 && COMPILE_TEST)

This dependency does not make sense anymore and can be simplified
removing all the COMPILE_TEST part.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202305160221.9XgweObz-lkp@intel.com/
Fixes: e3e7b13bffae ("serial: allow COMPILE_TEST for some drivers")
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/20230523085902.75837-3-herve.codina@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250_tegra: Fix an error handling path in tegra_uart_probe() 2023-06-09T08:48:22+00:00 Christophe JAILLET christophe.jaillet@wanadoo.fr 2023-05-14T11:25:42+00:00 b84462c0c7c873a687aad2025e876f097fe6562e commit 134f49dec0b6aca3259cd8259de4c572048bd207 upstream. If an error occurs after reset_control_deassert(), it must be re-asserted, as already done in the .remove() function. Fixes: c6825c6395b7 ("serial: 8250_tegra: Create Tegra specific 8250 driver") Cc: stable <stable@kernel.org> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Link: https://lore.kernel.org/r/f8130f35339cc80edc6b9aac4bb2a60b60a226bf.1684063511.git.christophe.jaillet@wanadoo.fr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 134f49dec0b6aca3259cd8259de4c572048bd207 upstream.

If an error occurs after reset_control_deassert(), it must be re-asserted,
as already done in the .remove() function.

Fixes: c6825c6395b7 ("serial: 8250_tegra: Create Tegra specific 8250 driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/f8130f35339cc80edc6b9aac4bb2a60b60a226bf.1684063511.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: fsl_lpuart: use UARTCTRL_TXINV to send break instead of UARTCTRL_SBK 2023-06-09T08:48:17+00:00 Sherry Sun sherry.sun@nxp.com 2023-05-19T09:47:51+00:00 55eb7a45276f9f9e3e307556dae79a60caac6f43 commit 2474e05467c00f7d51af3039b664de6886325257 upstream. LPUART IP now has two known bugs, one is that CTS has higher priority than the break signal, which causes the break signal sending through UARTCTRL_SBK may impacted by the CTS input if the HW flow control is enabled. It exists on all platforms we support in this driver. So we add a workaround patch for this issue: commit c4c81db5cf8b ("tty: serial: fsl_lpuart: disable the CTS when send break signal"). Another IP bug is i.MX8QM LPUART may have an additional break character being sent after SBK was cleared. It may need to add some delay between clearing SBK and re-enabling CTS to ensure that the SBK latch are completely cleared. But we found that during the delay period before CTS is enabled, there is still a risk that Bluetooth data in TX FIFO may be sent out during this period because of break off and CTS disabled(even if BT sets CTS line deasserted, data is still sent to BT). Due to this risk, we have to drop the CTS-disabling workaround for SBK bugs, use TXINV seems to be a better way to replace SBK feature and avoid above risk. Also need to disable the transmitter to prevent any data from being sent out during break, then invert the TX line to send break. Then disable the TXINV when turn off break and re-enable transmitter. Fixes: c4c81db5cf8b ("tty: serial: fsl_lpuart: disable the CTS when send break signal") Cc: stable <stable@kernel.org> Signed-off-by: Sherry Sun <sherry.sun@nxp.com> Link: https://lore.kernel.org/r/20230519094751.28948-1-sherry.sun@nxp.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 2474e05467c00f7d51af3039b664de6886325257 upstream.

LPUART IP now has two known bugs, one is that CTS has higher priority
than the break signal, which causes the break signal sending through
UARTCTRL_SBK may impacted by the CTS input if the HW flow control is
enabled. It exists on all platforms we support in this driver.
So we add a workaround patch for this issue: commit c4c81db5cf8b
("tty: serial: fsl_lpuart: disable the CTS when send break signal").

Another IP bug is i.MX8QM LPUART may have an additional break character
being sent after SBK was cleared. It may need to add some delay between
clearing SBK and re-enabling CTS to ensure that the SBK latch are
completely cleared.

But we found that during the delay period before CTS is enabled, there
is still a risk that Bluetooth data in TX FIFO may be sent out during
this period because of break off and CTS disabled(even if BT sets CTS
line deasserted, data is still sent to BT).

Due to this risk, we have to drop the CTS-disabling workaround for SBK
bugs, use TXINV seems to be a better way to replace SBK feature and
avoid above risk. Also need to disable the transmitter to prevent any
data from being sent out during break, then invert the TX line to send
break. Then disable the TXINV when turn off break and re-enable
transmitter.

Fixes: c4c81db5cf8b ("tty: serial: fsl_lpuart: disable the CTS when send break signal")
Cc: stable <stable@kernel.org>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20230519094751.28948-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: qcom-geni: fix enabling deactivated interrupt 2023-05-24T16:30:22+00:00 Krzysztof Kozlowski krzysztof.kozlowski@linaro.org 2023-05-05T15:23:01+00:00 a599be1bb34690dffd8dd1a4e555bf9efc68bb92 commit 5f949f140f73696f64acb89a1f16ff9153d017e0 upstream. The driver have a race, experienced only with PREEMPT_RT patchset: CPU0 | CPU1 ================================================================== qcom_geni_serial_probe | uart_add_one_port | | serdev_drv_probe | qca_serdev_probe | serdev_device_open | uart_open | uart_startup | qcom_geni_serial_startup | enable_irq | __irq_startup | WARN_ON() | IRQ not activated request_threaded_irq | irq_domain_activate_irq | The warning: 894000.serial: ttyHS1 at MMIO 0x894000 (irq = 144, base_baud = 0) is a MSM serial serial0: tty port ttyHS1 registered WARNING: CPU: 7 PID: 107 at kernel/irq/chip.c:241 __irq_startup+0x78/0xd8 ... qcom_geni_serial 894000.serial: serial engine reports 0 RX bytes in! Adding UART port triggers probe of child serial devices - serdev and eventually Qualcomm Bluetooth hci_qca driver. This opens UART port which enables the interrupt before it got activated in request_threaded_irq(). The issue originates in commit f3974413cf02 ("tty: serial: qcom_geni_serial: Wakeup IRQ cleanup") and discussion on mailing list [1]. However the above commit does not explain why the uart_add_one_port() is moved above requesting interrupt. [1] https://lore.kernel.org/all/5d9f3dfa.1c69fb81.84c4b.30bf@mx.google.com/ Fixes: f3974413cf02 ("tty: serial: qcom_geni_serial: Wakeup IRQ cleanup") Cc: <stable@vger.kernel.org> Cc: Stephen Boyd <swboyd@chromium.org> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Link: https://lore.kernel.org/r/20230505152301.2181270-1-krzysztof.kozlowski@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 5f949f140f73696f64acb89a1f16ff9153d017e0 upstream.

The driver have a race, experienced only with PREEMPT_RT patchset:

CPU0                         | CPU1
==================================================================
qcom_geni_serial_probe       |
  uart_add_one_port          |
                             | serdev_drv_probe
                             |   qca_serdev_probe
                             |     serdev_device_open
                             |       uart_open
                             |         uart_startup
                             |           qcom_geni_serial_startup
                             |             enable_irq
                             |               __irq_startup
                             |                 WARN_ON()
                             |                 IRQ not activated
  request_threaded_irq       |
    irq_domain_activate_irq  |

The warning:

  894000.serial: ttyHS1 at MMIO 0x894000 (irq = 144, base_baud = 0) is a MSM
  serial serial0: tty port ttyHS1 registered
  WARNING: CPU: 7 PID: 107 at kernel/irq/chip.c:241 __irq_startup+0x78/0xd8
  ...
  qcom_geni_serial 894000.serial: serial engine reports 0 RX bytes in!

Adding UART port triggers probe of child serial devices - serdev and
eventually Qualcomm Bluetooth hci_qca driver.  This opens UART port
which enables the interrupt before it got activated in
request_threaded_irq().  The issue originates in commit f3974413cf02
("tty: serial: qcom_geni_serial: Wakeup IRQ cleanup") and discussion on
mailing list [1].  However the above commit does not explain why the
uart_add_one_port() is moved above requesting interrupt.

[1] https://lore.kernel.org/all/5d9f3dfa.1c69fb81.84c4b.30bf@mx.google.com/

Fixes: f3974413cf02 ("tty: serial: qcom_geni_serial: Wakeup IRQ cleanup")
Cc: <stable@vger.kernel.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20230505152301.2181270-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250_exar: Add support for USR298x PCI Modems 2023-05-24T16:30:22+00:00 Andrew Davis afd@ti.com 2023-04-20T16:02:09+00:00 e3e52010822fcb005ff1d39745578d5e7292e0d0 commit 95d698869b404772cc8b72560df71548491c10bc upstream. Possibly the last PCI controller-based (i.e. not a soft/winmodem) dial-up modem one can still buy. Looks to have a stock XR17C154 PCI UART chip for communication, but for some reason when provisioning the PCI IDs they swapped the vendor and subvendor IDs. Otherwise this card would have worked out of the box. Searching online, some folks seem to not have this issue and others do, so it is possible only some batches of cards have this error. Create a new macro to handle the switched IDs and add support here. Signed-off-by: Andrew Davis <afd@ti.com> Cc: stable <stable@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20230420160209.28221-1-afd@ti.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 95d698869b404772cc8b72560df71548491c10bc upstream.

Possibly the last PCI controller-based (i.e. not a soft/winmodem)
dial-up modem one can still buy.

Looks to have a stock XR17C154 PCI UART chip for communication, but for
some reason when provisioning the PCI IDs they swapped the vendor and
subvendor IDs. Otherwise this card would have worked out of the box.

Searching online, some folks seem to not have this issue and others do,
so it is possible only some batches of cards have this error.

Create a new macro to handle the switched IDs and add support here.

Signed-off-by: Andrew Davis <afd@ti.com>
Cc: stable <stable@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230420160209.28221-1-afd@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: Add support for Advantech PCI-1611U card 2023-05-24T16:30:22+00:00 Vitaliy Tomin tomin@iszf.irk.ru 2023-04-23T03:45:12+00:00 bb6cc3e05c2c36e75147933fff189ea8ae6b1621 commit d2b00516de0e1d696724247098f6733a6ea53908 upstream. Add support for Advantech PCI-1611U card Advantech provides opensource drivers for this and many others card based on legacy copy of 8250_pci driver called adv950 https://www.advantech.com/emt/support/details/driver?id=1-TDOIMJ It is hard to maintain to run as out of tree module on newer kernels. Just adding PCI ID to kernel 8250_pci works perfect. Signed-off-by: Vitaliy Tomin <tomin@iszf.irk.ru> Cc: stable <stable@kernel.org> Link: https://lore.kernel.org/r/20230423034512.2671157-1-tomin@iszf.irk.ru Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d2b00516de0e1d696724247098f6733a6ea53908 upstream.

Add support for Advantech PCI-1611U card

Advantech provides opensource drivers for this and many others card
based on legacy copy of 8250_pci driver called adv950

https://www.advantech.com/emt/support/details/driver?id=1-TDOIMJ

It is hard to maintain to run as out of tree module on newer kernels.
Just adding PCI ID to kernel 8250_pci works perfect.

Signed-off-by: Vitaliy Tomin <tomin@iszf.irk.ru>
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/20230423034512.2671157-1-tomin@iszf.irk.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250_bcm7271: fix leak in `brcmuart_probe` 2023-05-24T16:30:15+00:00 Doug Berger opendmb@gmail.com 2023-04-27T18:19:16+00:00 56a81445b8e4b8906d557518c5dae3ddbb447d1e [ Upstream commit f264f2f6f4788dc031cef60a0cf2881902736709 ] Smatch reports: drivers/tty/serial/8250/8250_bcm7271.c:1120 brcmuart_probe() warn: 'baud_mux_clk' from clk_prepare_enable() not released on lines: 1032. The issue is fixed by using a managed clock. Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver") Reported-by: XuDong Liu <m202071377@hust.edu.cn> Link: https://lore.kernel.org/lkml/20230424125100.4783-1-m202071377@hust.edu.cn/ Signed-off-by: Doug Berger <opendmb@gmail.com> Acked-by: Florian Fainelli <f.fainelli@gmail.com> Link: https://lore.kernel.org/r/20230427181916.2983697-3-opendmb@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit f264f2f6f4788dc031cef60a0cf2881902736709 ]

Smatch reports:
drivers/tty/serial/8250/8250_bcm7271.c:1120 brcmuart_probe() warn:
'baud_mux_clk' from clk_prepare_enable() not released on lines: 1032.

The issue is fixed by using a managed clock.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Reported-by: XuDong Liu <m202071377@hust.edu.cn>
Link: https://lore.kernel.org/lkml/20230424125100.4783-1-m202071377@hust.edu.cn/
Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230427181916.2983697-3-opendmb@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
serial: 8250_bcm7271: balance clk_enable calls 2023-05-24T16:30:15+00:00 Doug Berger opendmb@gmail.com 2023-04-27T18:19:15+00:00 5ea03de0199a3efa25724241624f0b17a738f436 [ Upstream commit 8a3b5477256a54ae4a470dcebbcf8cdc18e4696d ] The sw_baud clock must be disabled when the device driver is not connected to the device. This now occurs when probe fails and upon remove. Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver") Reported-by: XuDong Liu <m202071377@hust.edu.cn> Link: https://lore.kernel.org/lkml/20230424125100.4783-1-m202071377@hust.edu.cn/ Signed-off-by: Doug Berger <opendmb@gmail.com> Acked-by: Florian Fainelli <f.fainelli@gmail.com> Link: https://lore.kernel.org/r/20230427181916.2983697-2-opendmb@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 8a3b5477256a54ae4a470dcebbcf8cdc18e4696d ]

The sw_baud clock must be disabled when the device driver is not
connected to the device. This now occurs when probe fails and
upon remove.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Reported-by: XuDong Liu <m202071377@hust.edu.cn>
Link: https://lore.kernel.org/lkml/20230424125100.4783-1-m202071377@hust.edu.cn/
Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230427181916.2983697-2-opendmb@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
serial: arc_uart: fix of_iomap leak in `arc_serial_probe` 2023-05-24T16:30:15+00:00 Ke Zhang m202171830@hust.edu.cn 2023-04-28T03:16:36+00:00 40a462313ba4f337a2b419e7fb4a670f3dd95e14 [ Upstream commit 8ab5fc55d7f65d58a3c3aeadf11bdf60267cd2bd ] Smatch reports: drivers/tty/serial/arc_uart.c:631 arc_serial_probe() warn: 'port->membase' from of_iomap() not released on lines: 631. In arc_serial_probe(), if uart_add_one_port() fails, port->membase is not released, which would cause a resource leak. To fix this, I replace of_iomap with devm_platform_ioremap_resource. Fixes: 8dbe1d5e09a7 ("serial/arc: inline the probe helper") Signed-off-by: Ke Zhang <m202171830@hust.edu.cn> Reviewed-by: Dongliang Mu <dzm91@hust.edu.cn> Link: https://lore.kernel.org/r/20230428031636.44642-1-m202171830@hust.edu.cn Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 8ab5fc55d7f65d58a3c3aeadf11bdf60267cd2bd ]

Smatch reports:

drivers/tty/serial/arc_uart.c:631 arc_serial_probe() warn:
'port->membase' from of_iomap() not released on lines: 631.

In arc_serial_probe(), if uart_add_one_port() fails,
port->membase is not released, which would cause a resource leak.

To fix this, I replace of_iomap with devm_platform_ioremap_resource.

Fixes: 8dbe1d5e09a7 ("serial/arc: inline the probe helper")
Signed-off-by: Ke Zhang <m202171830@hust.edu.cn>
Reviewed-by: Dongliang Mu <dzm91@hust.edu.cn>
Link: https://lore.kernel.org/r/20230428031636.44642-1-m202171830@hust.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
serial: 8250: Reinit port->pm on port specific driver unbind 2023-05-24T16:30:09+00:00 Tony Lindgren tony@atomide.com 2023-04-18T10:14:06+00:00 8e596aed5f2f98cf3e6e98d6fe1d689f4a319308 [ Upstream commit 04e82793f068d2f0ffe62fcea03d007a8cdc16a7 ] When we unbind a serial port hardware specific 8250 driver, the generic serial8250 driver takes over the port. After that we see an oops about 10 seconds later. This can produce the following at least on some TI SoCs: Unhandled fault: imprecise external abort (0x1406) Internal error: : 1406 [#1] SMP ARM Turns out that we may still have the serial port hardware specific driver port->pm in use, and serial8250_pm() tries to call it after the port specific driver is gone: serial8250_pm [8250_base] from uart_change_pm+0x54/0x8c [serial_base] uart_change_pm [serial_base] from uart_hangup+0x154/0x198 [serial_base] uart_hangup [serial_base] from __tty_hangup.part.0+0x328/0x37c __tty_hangup.part.0 from disassociate_ctty+0x154/0x20c disassociate_ctty from do_exit+0x744/0xaac do_exit from do_group_exit+0x40/0x8c do_group_exit from __wake_up_parent+0x0/0x1c Let's fix the issue by calling serial8250_set_defaults() in serial8250_unregister_port(). This will set the port back to using the serial8250 default functions, and sets the port->pm to point to serial8250_pm. Signed-off-by: Tony Lindgren <tony@atomide.com> Link: https://lore.kernel.org/r/20230418101407.12403-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 04e82793f068d2f0ffe62fcea03d007a8cdc16a7 ]

When we unbind a serial port hardware specific 8250 driver, the generic
serial8250 driver takes over the port. After that we see an oops about 10
seconds later. This can produce the following at least on some TI SoCs:

Unhandled fault: imprecise external abort (0x1406)
Internal error: : 1406 [#1] SMP ARM

Turns out that we may still have the serial port hardware specific driver
port->pm in use, and serial8250_pm() tries to call it after the port
specific driver is gone:

serial8250_pm [8250_base] from uart_change_pm+0x54/0x8c [serial_base]
uart_change_pm [serial_base] from uart_hangup+0x154/0x198 [serial_base]
uart_hangup [serial_base] from __tty_hangup.part.0+0x328/0x37c
__tty_hangup.part.0 from disassociate_ctty+0x154/0x20c
disassociate_ctty from do_exit+0x744/0xaac
do_exit from do_group_exit+0x40/0x8c
do_group_exit from __wake_up_parent+0x0/0x1c

Let's fix the issue by calling serial8250_set_defaults() in
serial8250_unregister_port(). This will set the port back to using
the serial8250 default functions, and sets the port->pm to point to
serial8250_pm.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20230418101407.12403-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>