linux-stable.git/drivers/tty/serial, branch linux-6.16.y

serial: stm32: allow selecting console when the driver is module

2025-10-12T11:01:03+00:00

commit cc4d900d0d6d8dd5c41832a93ff3cfa629a78f9a upstream.

Console can be enabled on the UART compile as module.
Change dependency to allow console mode when the driver is built as module.

Fixes: 48a6092fb41fa ("serial: stm32-usart: Add STM32 USART Driver")
Cc: stable@vger.kernel.org
Signed-off-by: Raphael Gallais-Pou 
Link: https://lore.kernel.org/r/20250822141923.61133-1-raphael.gallais-pou@foss.st.com
Signed-off-by: Greg Kroah-Hartman

serial: sc16is7xx: fix bug in flow control levels init

2025-09-19T14:37:34+00:00

commit 535fd4c98452c87537a40610abba45daf5761ec6 upstream.

When trying to set MCR[2], XON1 is incorrectly accessed instead. And when
writing to the TCR register to configure flow control levels, we are
incorrectly writing to the MSR register. The default value of $00 is then
used for TCR, which means that selectable trigger levels in FCR are used
in place of TCR.

TCR/TLR access requires EFR[4] (enable enhanced functions) and MCR[2]
to be set. EFR[4] is already set in probe().

MCR access requires LCR[7] to be zero.

Since LCR is set to $BF when trying to set MCR[2], XON1 is incorrectly
accessed instead because MCR shares the same address space as XON1.

Since MCR[2] is unmodified and still zero, when writing to TCR we are in
fact writing to MSR because TCR/TLR registers share the same address space
as MSR/SPR.

Fix by first removing useless reconfiguration of EFR[4] (enable enhanced
functions), as it is already enabled in sc16is7xx_probe() since commit
43c51bb573aa ("sc16is7xx: make sure device is in suspend once probed").
Now LCR is $00, which means that MCR access is enabled.

Also remove regcache_cache_bypass() calls since we no longer access the
enhanced registers set, and TCR is already declared as volatile (in fact
by declaring MSR as volatile, which shares the same address).

Finally disable access to TCR/TLR registers after modifying them by
clearing MCR[2].

Note: the comment about "... and internal clock div" is wrong and can be
      ignored/removed as access to internal clock div registers (DLL/DLH)
      is permitted only when LCR[7] is logic 1, not when enhanced features
      is enabled. And DLL/DLH access is not needed in sc16is7xx_startup().

Fixes: dfeae619d781 ("serial: sc16is7xx")
Cc: stable@vger.kernel.org
Signed-off-by: Hugo Villeneuve 
Link: https://lore.kernel.org/r/20250731124451.1108864-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman

serial: 8250: fix panic due to PSLVERR

2025-08-28T14:34:11+00:00

commit 7f8fdd4dbffc05982b96caf586f77a014b2a9353 upstream.

When the PSLVERR_RESP_EN parameter is set to 1, the device generates
an error response if an attempt is made to read an empty RBR (Receive
Buffer Register) while the FIFO is enabled.

In serial8250_do_startup(), calling serial_port_out(port, UART_LCR,
UART_LCR_WLEN8) triggers dw8250_check_lcr(), which invokes
dw8250_force_idle() and serial8250_clear_and_reinit_fifos(). The latter
function enables the FIFO via serial_out(p, UART_FCR, p->fcr).
Execution proceeds to the serial_port_in(port, UART_RX).
This satisfies the PSLVERR trigger condition.

When another CPU (e.g., using printk()) is accessing the UART (UART
is busy), the current CPU fails the check (value & ~UART_LCR_SPAR) ==
(lcr & ~UART_LCR_SPAR) in dw8250_check_lcr(), causing it to enter
dw8250_force_idle().

Put serial_port_out(port, UART_LCR, UART_LCR_WLEN8) under the port->lock
to fix this issue.

Panic backtrace:
[    0.442336] Oops - unknown exception [#1]
[    0.442343] epc : dw8250_serial_in32+0x1e/0x4a
[    0.442351]  ra : serial8250_do_startup+0x2c8/0x88e
...
[    0.442416] console_on_rootfs+0x26/0x70

Fixes: c49436b657d0 ("serial: 8250_dw: Improve unwritable LCR workaround")
Link: https://lore.kernel.org/all/84cydt5peu.fsf@jogness.linutronix.de/T/
Signed-off-by: Yunhui Cui 
Reviewed-by: John Ogness 
Cc: stable 
Link: https://lore.kernel.org/r/20250723023322.464-2-cuiyunhui@bytedance.com
[ adapted to inline code structure without separate serial8250_initialize helper function ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

tty: serial: fix print format specifiers

2025-08-20T16:41:03+00:00

[ Upstream commit 33a2515abd45c64911955ff1da179589db54f99f ]

The serial info sometimes produces negative TX/RX counts. E.g.:

3: uart:FSL_LPUART mmio:0x02970000 irq:46 tx:-1595870545 rx:339619
RTS|CTS|DTR|DSR|CD

It appears that the print format specifiers don't match with the types of
the respective variables. E.g.: All of the fields in struct uart_icount
are u32, but the format specifier used is %d, even though u32 is unsigned
and %d is for signed integers. Update drivers/tty/serial/serial_core.c
to use the proper format specifiers. Reference
https://docs.kernel.org/core-api/printk-formats.html as the documentation
for what format specifiers are the proper ones to use for a given C type.

Signed-off-by: Joseph Tilahun 
Link: https://lore.kernel.org/r/20250610065653.3750067-1-jtilahun@astranis.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

pch_uart: Fix dma_sync_sg_for_device() nents value

2025-07-09T11:43:02+00:00

The dma_sync_sg_for_device() functions should be called with the same
nents as the dma_map_sg(), not the value the map function returned
according to the documentation in Documentation/core-api/dma-api.rst:450:
	With the sync_sg API, all the parameters must be the same
	as those passed into the sg mapping API.

Fixes: da3564ee027e ("pch_uart: add multi-scatter processing")
Cc: stable 
Signed-off-by: Thomas Fourier 
Reviewed-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/20250701113452.18590-2-fourier.thomas@gmail.com
Signed-off-by: Greg Kroah-Hartman

serial: core: fix OF node leak

2025-07-09T11:41:48+00:00

Make sure to drop the OF node reference taken when initialising the
control and port devices when the devices are later released.

Fixes: d36f0e9a0002 ("serial: core: restore of_node information in sysfs")
Cc: Aidan Stewart 
Signed-off-by: Johan Hovold 
Link: https://lore.kernel.org/r/20250708085817.16070-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman

serial: imx: Restore original RXTL for console to fix data loss

2025-06-24T14:34:21+00:00

Commit 7a637784d517 ("serial: imx: reduce RX interrupt frequency")
introduced a regression on the i.MX6UL EVK board. The issue can be
reproduced with the following steps:

- Open vi on the board.
- Paste a text file (~150 characters).
- Save the file, then repeat the process.
- Compare the sha256sum of the saved files.

The checksums do not match due to missing characters or entire lines.

Fix this by restoring the RXTL value to 1 when the UART is used as a
console.

This ensures timely RX interrupts and reliable data reception in console
mode.

With this change, pasted content is saved correctly, and checksums are
always consistent.

Cc: stable 
Fixes: 7a637784d517 ("serial: imx: reduce RX interrupt frequency")
Signed-off-by: Fabio Estevam 
Reviewed-by: Stefan Wahren 
Link: https://lore.kernel.org/r/20250619114617.2791939-1-festevam@gmail.com
Signed-off-by: Greg Kroah-Hartman

serial: core: restore of_node information in sysfs

2025-06-19T11:27:48+00:00

Since in v6.8-rc1, the of_node symlink under tty devices is
missing. This breaks any udev rules relying on this information.

Link the of_node information in the serial controller device with the
parent defined in the device tree. This will also apply to the serial
device which takes the serial controller as a parent device.

Fixes: b286f4e87e32 ("serial: core: Move tty and serdev to be children of serial core port device")
Cc: stable@vger.kernel.org
Signed-off-by: Aidan Stewart 
Link: https://lore.kernel.org/r/20250617164819.13912-1-astewart@tektelic.com
Signed-off-by: Greg Kroah-Hartman

treewide, timers: Rename from_timer() to timer_container_of()

2025-06-08T07:07:37+00:00

Move this API to the canonical timer_*() namespace.

[ tglx: Redone against pre rc1 ]

Signed-off-by: Ingo Molnar 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com

tty: serial: 8250_omap: fix TX with DMA for am33xx

2025-05-22T05:50:45+00:00

Commit 1788cf6a91d9 ("tty: serial: switch from circ_buf to kfifo")
introduced an error in the TX DMA handling for 8250_omap.

When the OMAP_DMA_TX_KICK flag is set, the "skip_byte" is pulled from
the kfifo and emitted directly in order to start the DMA. While the
kfifo is updated, dma->tx_size is not decreased. This leads to
uart_xmit_advance() called in omap_8250_dma_tx_complete() advancing the
kfifo by one too much.

In practice, transmitting N bytes has been seen to result in the last
N-1 bytes being sent repeatedly.

This change fixes the problem by moving all of the dma setup after the
OMAP_DMA_TX_KICK handling and using kfifo_len() instead of the DMA size
for the 4-byte cutoff check. This slightly changes the behaviour at
buffer wraparound, but it still transmits the correct bytes somehow.

Now, the "skip_byte" would no longer be accounted to the stats. As
previously, dma->tx_size included also this skip byte, up->icount.tx was
updated by aforementioned uart_xmit_advance() in
omap_8250_dma_tx_complete(). Fix this by using the uart_fifo_out()
helper instead of bare kfifo_get().

Based on patch by Mans Rullgard 

Signed-off-by: "Jiri Slaby (SUSE)" 
Fixes: 1788cf6a91d9 ("tty: serial: switch from circ_buf to kfifo")
Link: https://lore.kernel.org/all/20250506150748.3162-1-mans@mansr.com/
Reported-by: Mans Rullgard 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250522053835.3495975-1-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman