syzbot is reporting lockdep warning upon

  int disc = 7;
  ioctl(open("/dev/ttyS3", O_RDONLY), TIOCSETD, &disc);

sequence. Do like what commit 5f1149d2f4bf ("serial: drop debugging
WARN_ON_ONCE() from uart_put_char()") does.

Reported-by: syzbot+f78380e4eae53c64125c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f78380e4eae53c64125c
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/d775ae2d-a2ac-439e-8e2b-134749f60f30@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit d49216438139
("serial: sc16is7xx: split into core and I2C/SPI parts (core)")
removed Kconfig SPI_MASTER or I2C dependency for SERIAL_SC16IS7XX (core).
This removal was done because I inadvertently misinterpreted some review
comments.

Because of that, the driver question now pops up if both I2C and
SPI_MASTER are disabled.

Re-add Kconfig SPI_MASTER or I2C dependency to fix the problem.

Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Fixes: d49216438139 ("serial: sc16is7xx: split into core and I2C/SPI parts (core)")
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20240603152601.3689319-3-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit d49216438139
("serial: sc16is7xx: split into core and I2C/SPI parts (core)")
renamed SERIAL_SC16IS7XX_CORE by SERIAL_SC16IS7XX. This means that some
configs should have been updated when I submitted the original patch, but
unfortunately they were not. Geert mentioned for example:
    arch/mips/configs/cu1??0-neo_defconfig

Rename SERIAL_SC16IS7XX to SERIAL_SC16IS7XX_CORE so that existing configs
will still work correctly.

Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Fixes: d49216438139 ("serial: sc16is7xx: split into core and I2C/SPI parts (core)")
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20240603152601.3689319-2-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Recently, suspend testing on sc7180-trogdor based devices has started
to sometimes fail with messages like this:

  port a88000.serial:0.0: PM: calling pm_runtime_force_suspend+0x0/0xf8 @ 28934, parent: a88000.serial:0
  port a88000.serial:0.0: PM: dpm_run_callback(): pm_runtime_force_suspend+0x0/0xf8 returns -16
  port a88000.serial:0.0: PM: pm_runtime_force_suspend+0x0/0xf8 returned -16 after 33 usecs
  port a88000.serial:0.0: PM: failed to suspend: error -16

I could reproduce these problems by logging in via an agetty on the
debug serial port (which was _not_ used for kernel console) and
running:
  cat /var/log/messages
...and then (via an SSH session) forcing a few suspend/resume cycles.

Tracing through the code and doing some printf()-based debugging shows
that the -16 (-EBUSY) comes from the recently added
serial_port_runtime_suspend().

The idea of the serial_port_runtime_suspend() function is to prevent
the port from being _runtime_ suspended if it still has bytes left to
transmit. Having bytes left to transmit isn't a reason to block
_system_ suspend, though. If a serdev device in the kernel needs to
block system suspend it should block its own suspend and it can use
serdev_device_wait_until_sent() to ensure bytes are sent.

The DEFINE_RUNTIME_DEV_PM_OPS() used by the serial_port code means
that the system suspend function will be pm_runtime_force_suspend().
In pm_runtime_force_suspend() we can see that before calling the
runtime suspend function we'll call pm_runtime_disable(). This should
be a reliable way to detect that we're called from system suspend and
that we shouldn't look for busyness.

Fixes: 43066e32227e ("serial: port: Don't suspend if the port is still busy")
Cc: stable@vger.kernel.org
Reviewed-by: Tony Lindgren <tony.lindgren@linux.intel.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240531080914.v3.1.I2395e66cf70c6e67d774c56943825c289b9c13e4@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The FIFO is 64 bytes, but the FCR is configured to fire the TX interrupt
when the FIFO is half empty (bit 3 = 0). Thus, we should only write 32
bytes when a TX interrupt occurs.

This fixes a problem observed on the PXA168 that dropped a bunch of TX
bytes during large transmissions.

Fixes: ab28f51c77cd ("serial: rewrite pxa2xx-uart to use 8250_core")
Signed-off-by: Doug Brown <doug@schmorgal.com>
Link: https://lore.kernel.org/r/20240519191929.122202-1-doug@schmorgal.com
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit d9666dfb314e1ffd6eb9c3c4243fe3e094c047a7.

The container of the struct dw8250_port_data is private to the actual
driver. In particular, 8250_lpss and 8250_dw use different data types
that are assigned to the UART port private_data. Hence, it must not
be used outside the specific driver.

Fix the mistake made in the past by moving the respective definitions
to the specific driver.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240514190730.2787071-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The container of the struct dw8250_port_data is private to the actual
driver. In particular, 8250_lpss and 8250_dw use different data types
that are assigned to the UART port private_data. Hence, it must not
be used outside the specific driver.

Currently the only cpr_val is required by the common code, make it
be available via struct dw8250_port_data.

This fixes the UART breakage on Intel Galileo boards.

Fixes: 593dea000bc1 ("serial: 8250: dw: Allow to use a fallback CPR value if not synthesized")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240514190730.2787071-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull tty/serial fixes from Greg KH:
 "Here are some small TTY and Serial driver fixes that missed the
  6.9-final merge window, but have been in my tree for weeks (my fault,
  travel caused me to miss this)

  These fixes include:

   - more n_gsm fixes for reported problems

   - 8520_mtk driver fix

   - 8250_bcm7271 driver fix

   - sc16is7xx driver fix

  All of these have been in linux-next for weeks without any reported
  problems"

* tag 'tty-6.10-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: sc16is7xx: fix bug in sc16is7xx_set_baud() when using prescaler
  serial: 8250_bcm7271: use default_mux_rate if possible
  serial: 8520_mtk: Set RTS on shutdown for Rx in-band wakeup
  tty: n_gsm: fix missing receive state reset after mode switch
  tty: n_gsm: fix possible out-of-bounds in gsm0_receive()

Pull tty / serial updates from Greg KH:
 "Here is the big set of tty/serial driver changes for 6.10-rc1.
  Included in here are:

   - Usual good set of api cleanups and evolution by Jiri Slaby to make
     the serial interfaces move out of the 1990's by using kfifos
     instead of hand-rolling their own logic.

   - 8250_exar driver updates

   - max3100 driver updates

   - sc16is7xx driver updates

   - exar driver updates

   - sh-sci driver updates

   - tty ldisc api addition to help refuse bindings

   - other smaller serial driver updates

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (113 commits)
  serial: Clear UPF_DEAD before calling tty_port_register_device_attr_serdev()
  serial: imx: Raise TX trigger level to 8
  serial: 8250_pnp: Simplify "line" related code
  serial: sh-sci: simplify locking when re-issuing RXDMA fails
  serial: sh-sci: let timeout timer only run when DMA is scheduled
  serial: sh-sci: describe locking requirements for invalidating RXDMA
  serial: sh-sci: protect invalidating RXDMA on shutdown
  tty: add the option to have a tty reject a new ldisc
  serial: core: Call device_set_awake_path() for console port
  dt-bindings: serial: brcm,bcm2835-aux-uart: convert to dtschema
  tty: serial: uartps: Add support for uartps controller reset
  arm64: zynqmp: Add resets property for UART nodes
  dt-bindings: serial: cdns,uart: Add optional reset property
  serial: 8250_pnp: Switch to DEFINE_SIMPLE_DEV_PM_OPS()
  serial: 8250_exar: Keep the includes sorted
  serial: 8250_exar: Make type of bit the same in exar_ee_*_bit()
  serial: 8250_exar: Use BIT() in exar_ee_read()
  serial: 8250_exar: Switch to use dev_err_probe()
  serial: 8250_exar: Return directly from switch-cases
  serial: 8250_exar: Decrease indentation level
  ...

Pull pci updates from Bjorn Helgaas:
 "Enumeration:

   - Skip E820 checks for MCFG ECAM regions for new (2016+) machines,
     since there's no requirement to describe them in E820 and some
     platforms require ECAM to work (Bjorn Helgaas)

   - Rename PCI_IRQ_LEGACY to PCI_IRQ_INTX to be more specific (Damien
     Le Moal)

   - Remove last user and pci_enable_device_io() (Heiner Kallweit)

   - Wait for Link Training==0 to avoid possible race (Ilpo Järvinen)

   - Skip waiting for devices that have been disconnected while
     suspended (Ilpo Järvinen)

   - Clear Secondary Status errors after enumeration since Master Aborts
     and Unsupported Request errors are an expected part of enumeration
     (Vidya Sagar)

  MSI:

   - Remove unused IMS (Interrupt Message Store) support (Bjorn Helgaas)

  Error handling:

   - Mask Genesys GL975x SD host controller Replay Timer Timeout
     correctable errors caused by a hardware defect; the errors cause
     interrupts that prevent system suspend (Kai-Heng Feng)

   - Fix EDR-related _DSM support, which previously evaluated revision 5
     but assumed revision 6 behavior (Kuppuswamy Sathyanarayanan)

  ASPM:

   - Simplify link state definitions and mask calculation (Ilpo
     Järvinen)

  Power management:

   - Avoid D3cold for HP Pavilion 17 PC/1972 PCIe Ports, where BIOS
     apparently doesn't know how to put them back in D0 (Mario
     Limonciello)

  CXL:

   - Support resetting CXL devices; special handling required because
     CXL Ports mask Secondary Bus Reset by default (Dave Jiang)

  DOE:

   - Support DOE Discovery Version 2 (Alexey Kardashevskiy)

  Endpoint framework:

   - Set endpoint BAR to be 64-bit if the driver says that's all the
     device supports, in addition to doing so if the size is >2GB
     (Niklas Cassel)

   - Simplify endpoint BAR allocation and setting interfaces (Niklas
     Cassel)

  Cadence PCIe controller driver:

   - Drop DT binding redundant msi-parent and pci-bus.yaml (Krzysztof
     Kozlowski)

  Cadence PCIe endpoint driver:

   - Configure endpoint BARs to be 64-bit based on the BAR type, not the
     BAR value (Niklas Cassel)

  Freescale Layerscape PCIe controller driver:

   - Convert DT binding to YAML (Frank Li)

  MediaTek MT7621 PCIe controller driver:

   - Add DT binding missing 'reg' property for child Root Ports
     (Krzysztof Kozlowski)

   - Fix theoretical string truncation in PHY name (Sergio Paracuellos)

  NVIDIA Tegra194 PCIe controller driver:

   - Return success for endpoint probe instead of falling through to the
     failure path (Vidya Sagar)

  Renesas R-Car PCIe controller driver:

   - Add DT binding missing IOMMU properties (Geert Uytterhoeven)

   - Add DT binding R-Car V4H compatible for host and endpoint mode
     (Yoshihiro Shimoda)

  Rockchip PCIe controller driver:

   - Configure endpoint BARs to be 64-bit based on the BAR type, not the
     BAR value (Niklas Cassel)

   - Add DT binding missing maxItems to ep-gpios (Krzysztof Kozlowski)

   - Set the Subsystem Vendor ID, which was previously zero because it
     was masked incorrectly (Rick Wertenbroek)

  Synopsys DesignWare PCIe controller driver:

   - Restructure DBI register access to accommodate devices where this
     requires Refclk to be active (Manivannan Sadhasivam)

   - Remove the deinit() callback, which was only need by the
     pcie-rcar-gen4, and do it directly in that driver (Manivannan
     Sadhasivam)

   - Add dw_pcie_ep_cleanup() so drivers that support PERST# can clean
     up things like eDMA (Manivannan Sadhasivam)

   - Rename dw_pcie_ep_exit() to dw_pcie_ep_deinit() to make it parallel
     to dw_pcie_ep_init() (Manivannan Sadhasivam)

   - Rename dw_pcie_ep_init_complete() to dw_pcie_ep_init_registers() to
     reflect the actual functionality (Manivannan Sadhasivam)

   - Call dw_pcie_ep_init_registers() directly from all the glue
     drivers, not just those that require active Refclk from the host
     (Manivannan Sadhasivam)

   - Remove the "core_init_notifier" flag, which was an obscure way for
     glue drivers to indicate that they depend on Refclk from the host
     (Manivannan Sadhasivam)

  TI J721E PCIe driver:

   - Add DT binding J784S4 SoC Device ID (Siddharth Vadapalli)

   - Add DT binding J722S SoC support (Siddharth Vadapalli)

  TI Keystone PCIe controller driver:

   - Add DT binding missing num-viewport, phys and phy-name properties
     (Jan Kiszka)

  Miscellaneous:

   - Constify and annotate with __ro_after_init (Heiner Kallweit)

   - Convert DT bindings to YAML (Krzysztof Kozlowski)

   - Check for kcalloc() failure in of_pci_prop_intr_map() (Duoming
     Zhou)"

* tag 'pci-v6.10-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci: (97 commits)
  PCI: Do not wait for disconnected devices when resuming
  x86/pci: Skip early E820 check for ECAM region
  PCI: Remove unused pci_enable_device_io()
  ata: pata_cs5520: Remove unnecessary call to pci_enable_device_io()
  PCI: Update pci_find_capability() stub return types
  PCI: Remove PCI_IRQ_LEGACY
  scsi: vmw_pvscsi: Do not use PCI_IRQ_LEGACY instead of PCI_IRQ_LEGACY
  scsi: pmcraid: Use PCI_IRQ_INTX instead of PCI_IRQ_LEGACY
  scsi: mpt3sas: Use PCI_IRQ_INTX instead of PCI_IRQ_LEGACY
  scsi: megaraid_sas: Use PCI_IRQ_INTX instead of PCI_IRQ_LEGACY
  scsi: ipr: Use PCI_IRQ_INTX instead of PCI_IRQ_LEGACY
  scsi: hpsa: Use PCI_IRQ_INTX instead of PCI_IRQ_LEGACY
  scsi: arcmsr: Use PCI_IRQ_INTX instead of PCI_IRQ_LEGACY
  wifi: rtw89: Use PCI_IRQ_INTX instead of PCI_IRQ_LEGACY
  dt-bindings: PCI: rockchip,rk3399-pcie: Add missing maxItems to ep-gpios
  Revert "genirq/msi: Provide constants for PCI/IMS support"
  Revert "x86/apic/msi: Enable PCI/IMS"
  Revert "iommu/vt-d: Enable PCI/IMS"
  Revert "iommu/amd: Enable PCI/IMS"
  Revert "PCI/MSI: Provide IMS (Interrupt Message Store) support"
  ...