linux-stable.git/drivers/tty, branch linux-6.15.y

tty: serial: fix print format specifiers

2025-08-20T16:35:59+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

2025-07-24T06:58:23+00:00

commit 6c0e9f05c9d7875995b0e92ace71be947f280bbd upstream.

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

vt: add missing notification when switching back to text mode

2025-07-17T16:44:03+00:00

[ Upstream commit ff78538e07fa284ce08cbbcb0730daa91ed16722 ]

Programs using poll() on /dev/vcsa to be notified when VT changes occur
were missing one case: the switch from gfx to text mode.

Signed-off-by: Nicolas Pitre 
Link: https://lore.kernel.org/r/9o5ro928-0pp4-05rq-70p4-ro385n21n723@onlyvoer.pbz
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

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

2025-07-06T09:04:18+00:00

commit f23c52aafb1675ab1d1f46914556d8e29cbbf7b3 upstream.

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

2025-07-06T09:04:18+00:00

commit d36f0e9a0002f04f4d6dd9be908d58fe5bd3a279 upstream.

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

tty: serial: uartlite: register uart driver in init

2025-07-06T09:04:07+00:00

[ Upstream commit 6bd697b5fc39fd24e2aa418c7b7d14469f550a93 ]

When two instances of uart devices are probing, a concurrency race can
occur. If one thread calls uart_register_driver function, which first
allocates and assigns memory to 'uart_state' member of uart_driver
structure, the other instance can bypass uart driver registration and
call ulite_assign. This calls uart_add_one_port, which expects the uart
driver to be fully initialized. This leads to a kernel panic due to a
null pointer dereference:

[    8.143581] BUG: kernel NULL pointer dereference, address: 00000000000002b8
[    8.156982] #PF: supervisor write access in kernel mode
[    8.156984] #PF: error_code(0x0002) - not-present page
[    8.156986] PGD 0 P4D 0
...
[    8.180668] RIP: 0010:mutex_lock+0x19/0x30
[    8.188624] Call Trace:
[    8.188629]  ? __die_body.cold+0x1a/0x1f
[    8.195260]  ? page_fault_oops+0x15c/0x290
[    8.209183]  ? __irq_resolve_mapping+0x47/0x80
[    8.209187]  ? exc_page_fault+0x64/0x140
[    8.209190]  ? asm_exc_page_fault+0x22/0x30
[    8.209196]  ? mutex_lock+0x19/0x30
[    8.223116]  uart_add_one_port+0x60/0x440
[    8.223122]  ? proc_tty_register_driver+0x43/0x50
[    8.223126]  ? tty_register_driver+0x1ca/0x1e0
[    8.246250]  ulite_probe+0x357/0x4b0 [uartlite]

To prevent it, move uart driver registration in to init function. This
will ensure that uart_driver is always registered when probe function
is called.

Signed-off-by: Jakub Lewalski 
Signed-off-by: Elodie Decerle 
Link: https://lore.kernel.org/r/20250331160732.2042-1-elodie.decerle@nokia.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

8250: microchip: pci1xxxx: Add PCIe Hot reset disable support for Rev C0 and later devices

2025-07-06T09:04:07+00:00

[ Upstream commit c40b91e38eb8d4489def095d62ab476d45871323 ]

Systems that issue PCIe hot reset requests during a suspend/resume
cycle cause PCI1XXXX device revisions prior to C0 to get its UART
configuration registers reset to hardware default values. This results
in device inaccessibility and data transfer failures. Starting with
Revision C0, support was added in the device hardware (via the Hot
Reset Disable Bit) to allow resetting only the PCIe interface and its
associated logic, but preserving the UART configuration during a hot
reset. This patch enables the hot reset disable feature during suspend/
resume for C0 and later revisions of the device.

Signed-off-by: Rengarajan S 
Reviewed-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20250425145500.29036-1-rengarajan.s@microchip.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

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

2025-06-19T13:41:04+00:00

commit b495021a973e2468497689bd3e29b736747b896f upstream.

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

vt: remove VT_RESIZE and VT_RESIZEX from vt_compat_ioctl()

2025-06-19T13:40:32+00:00

[ Upstream commit c4c7ead7b86c1e7f11c64915b7e5bb6d2e242691 ]

They are listed amon those cmd values that "treat 'arg' as an integer"
which is wrong. They should instead fall into the default case. Probably
nobody ever relied on that code since 2009 but still.

Fixes: e92166517e3c ("tty: handle VT specific compat ioctls in vt driver")
Signed-off-by: Nicolas Pitre 
Reviewed-by: Jiri Slaby 
Link: https://lore.kernel.org/r/pr214s15-36r8-6732-2pop-159nq85o48r7@syhkavp.arg
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: Fix potential null-ptr-deref in mlb_usio_probe()

2025-06-19T13:40:29+00:00

[ Upstream commit 86bcae88c9209e334b2f8c252f4cc66beb261886 ]

devm_ioremap() can return NULL on error. Currently, mlb_usio_probe()
does not check for this case, which could result in a NULL pointer
dereference.

Add NULL check after devm_ioremap() to prevent this issue.

Fixes: ba44dc043004 ("serial: Add Milbeaut serial control")
Signed-off-by: Henry Martin 
Link: https://lore.kernel.org/r/20250403070339.64990-1-bsdhenrymartin@gmail.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin