linux-stable.git/drivers/tty, branch v6.1.129

serial: 8250_pci: add support for ASIX AX99100

2025-02-21T12:50:11+00:00

commit 0b32216557ce3b2a468d1282d99b428bf72ff532 upstream.

Each of the 4 PCI functions on ASIX AX99100 PCIe to Multi I/O
Controller can be configured as a single-port serial port controller.
The subvendor id is 0x1000 when configured as serial port and MSI
interrupts are supported.

Signed-off-by: Jiaqing Zhao 
Reviewed-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/20230724083933.3173513-4-jiaqing.zhao@linux.intel.com
Signed-off-by: Tomita Moeko 
Signed-off-by: Greg Kroah-Hartman

serial: 8250: Fix fifo underflow on flush

2025-02-21T12:50:04+00:00

commit 9e512eaaf8f4008c44ede3dfc0fbc9d9c5118583 upstream.

When flushing the serial port's buffer, uart_flush_buffer() calls
kfifo_reset() but if there is an outstanding DMA transfer then the
completion function will consume data from the kfifo via
uart_xmit_advance(), underflowing and leading to ongoing DMA as the
driver tries to transmit another 2^32 bytes.

This is readily reproduced with serial-generic and amidi sending even
short messages as closing the device on exit will wait for the fifo to
drain and in the underflow case amidi hangs for 30 seconds on exit in
tty_wait_until_sent().  A trace of that gives:

     kworker/1:1-84    [001]    51.769423: bprint:               serial8250_tx_dma: tx_size=3 fifo_len=3
           amidi-763   [001]    51.769460: bprint:               uart_flush_buffer: resetting fifo
 irq/21-fe530000-76    [000]    51.769474: bprint:               __dma_tx_complete: tx_size=3
 irq/21-fe530000-76    [000]    51.769479: bprint:               serial8250_tx_dma: tx_size=4096 fifo_len=4294967293
 irq/21-fe530000-76    [000]    51.781295: bprint:               __dma_tx_complete: tx_size=4096
 irq/21-fe530000-76    [000]    51.781301: bprint:               serial8250_tx_dma: tx_size=4096 fifo_len=4294963197
 irq/21-fe530000-76    [000]    51.793131: bprint:               __dma_tx_complete: tx_size=4096
 irq/21-fe530000-76    [000]    51.793135: bprint:               serial8250_tx_dma: tx_size=4096 fifo_len=4294959101
 irq/21-fe530000-76    [000]    51.804949: bprint:               __dma_tx_complete: tx_size=4096

Since the port lock is held in when the kfifo is reset in
uart_flush_buffer() and in __dma_tx_complete(), adding a flush_buffer
hook to adjust the outstanding DMA byte count is sufficient to avoid the
kfifo underflow.

Fixes: 9ee4b83e51f74 ("serial: 8250: Add support for dmaengine")
Cc: stable 
Signed-off-by: John Keeping 
Link: https://lore.kernel.org/r/20250208124148.1189191-1-jkeeping@inmusicbrands.com
Signed-off-by: Greg Kroah-Hartman

tty: xilinx_uartps: split sysrq handling

2025-02-21T12:49:54+00:00

commit b06f388994500297bb91be60ffaf6825ecfd2afe upstream.

lockdep detects the following circular locking dependency:

CPU 0                      CPU 1
========================== ============================
cdns_uart_isr()            printk()
  uart_port_lock(port)       console_lock()
			     cdns_uart_console_write()
                               if (!port->sysrq)
                                 uart_port_lock(port)
  uart_handle_break()
    port->sysrq = ...
  uart_handle_sysrq_char()
    printk()
      console_lock()

The fixed commit attempts to avoid this situation by only taking the
port lock in cdns_uart_console_write if port->sysrq unset. However, if
(as shown above) cdns_uart_console_write runs before port->sysrq is set,
then it will try to take the port lock anyway. This may result in a
deadlock.

Fix this by splitting sysrq handling into two parts. We use the prepare
helper under the port lock and defer handling until we release the lock.

Fixes: 74ea66d4ca06 ("tty: xuartps: Improve sysrq handling")
Signed-off-by: Sean Anderson 
Cc: stable@vger.kernel.org # c980248179d: serial: xilinx_uartps: Use port lock wrappers
Acked-by: John Ogness 
Link: https://lore.kernel.org/r/20250110213822.2107462-1-sean.anderson@linux.dev
Signed-off-by: Sean Anderson 
Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Do not probe the serial port if its slot in sci_ports[] is in use

2025-02-21T12:49:44+00:00

commit 9f7dea875cc7f9c1a56a5c688290634a59cd1420 upstream.

In the sh-sci driver, sci_ports[0] is used by earlycon. If the earlycon is
still active when sci_probe() is called and the new serial port is supposed
to map to sci_ports[0], return -EBUSY to prevent breaking the earlycon.

This situation should occurs in debug scenarios, and users should be
aware of the potential conflict.

Fixes: 0b0cced19ab1 ("serial: sh-sci: Add CONFIG_SERIAL_EARLYCON support")
Cc: stable@vger.kernel.org
Signed-off-by: Claudiu Beznea 
Link: https://lore.kernel.org/r/20250116182249.3828577-4-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Drop __initdata macro for port_cfg

2025-02-21T12:49:44+00:00

commit eaeee4225dba30bef4d424bdf134a07b7f423e8b upstream.

The port_cfg object is used by serial_console_write(), which serves as
the write function for the earlycon device. Marking port_cfg as __initdata
causes it to be freed after kernel initialization, resulting in earlycon
becoming unavailable thereafter. Remove the __initdata macro from port_cfg
to resolve this issue.

Fixes: 0b0cced19ab1 ("serial: sh-sci: Add CONFIG_SERIAL_EARLYCON support")
Cc: stable@vger.kernel.org
Reviewed-by: Geert Uytterhoeven 
Signed-off-by: Claudiu Beznea 
Fixes: 0b0cced19ab15c9e ("serial: sh-sci: Add CONFIG_SERIAL_EARLYCON support")
Link: https://lore.kernel.org/r/20250116182249.3828577-2-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

serial: 8250: Adjust the timeout for FIFO mode

2025-02-21T12:49:20+00:00

[ Upstream commit d91f98be26510f5f81ec66425bb0306d1ccd571a ]

After a console has written a record into UART_TX, it uses
wait_for_xmitr() to wait until the data has been sent out before
returning. However, wait_for_xmitr() will timeout after 10ms,
regardless if the data has been transmitted or not.

For single bytes, this timeout is sufficient even at very slow
baud rates, such as 1200bps. However, when FIFO mode is used,
there may be 64 bytes pushed into the FIFO at once. At a baud
rate of 115200bps, the 10ms timeout is still sufficient. But
when using lower baud rates (such as 57600bps), the timeout
is _not_ sufficient. This causes longer lines to be cut off,
resulting in lost and horribly misformatted output on the
console.

When using FIFO mode, take the number of bytes into account to
determine an appropriate maximum timeout. Increasing the timeout
does not affect performance since ideally the timeout never
occurs.

Fixes: 8f3631f0f6eb ("serial/8250: Use fifo in 8250 console driver")
Signed-off-by: John Ogness 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Wander Lairson Costa 
Reviewed-by: Petr Mladek 
Link: https://lore.kernel.org/r/20250107212702.169493-2-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: amba-pl011: fix build regression

2024-12-14T18:54:55+00:00

commit b5a23a60e8ab5711f4952912424347bf3864ce8d upstream.

When CONFIG_DMA_ENGINE is disabled, the driver now fails to build:

drivers/tty/serial/amba-pl011.c: In function 'pl011_unthrottle_rx':
drivers/tty/serial/amba-pl011.c:1822:16: error: 'struct uart_amba_port' has no member named 'using_rx_dma'
 1822 |         if (uap->using_rx_dma) {
      |                ^~
drivers/tty/serial/amba-pl011.c:1823:20: error: 'struct uart_amba_port' has no member named 'dmacr'
 1823 |                 uap->dmacr |= UART011_RXDMAE;
      |                    ^~
drivers/tty/serial/amba-pl011.c:1824:32: error: 'struct uart_amba_port' has no member named 'dmacr'
 1824 |                 pl011_write(uap->dmacr, uap, REG_DMACR);
      |                                ^~

Add the missing #ifdef check around these field accesses, matching
what other parts of this driver do.

Fixes: 2bcacc1c87ac ("serial: amba-pl011: Fix RX stall when DMA is used")
Cc: stable 
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202411140617.nkjeHhsK-lkp@intel.com/
Signed-off-by: Arnd Bergmann 
Link: https://lore.kernel.org/r/20241115110021.744332-1-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman

serial: 8250_dw: Add Sophgo SG2044 quirk

2024-12-14T18:54:49+00:00

[ Upstream commit cad4dda82c7eedcfc22597267e710ccbcf39d572 ]

SG2044 relys on an internal divisor when calculating bitrate, which
means a wrong clock for the most common bitrates. So add a quirk for
this uart device to skip the set rate call and only relys on the
internal UART divisor.

Reviewed-by: Andy Shevchenko 
Reviewed-by: Ilpo Järvinen 
Signed-off-by: Inochi Amaoto 
Link: https://lore.kernel.org/r/20241024062105.782330-4-inochiama@gmail.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: amba-pl011: Fix RX stall when DMA is used

2024-12-14T18:54:24+00:00

[ Upstream commit 2bcacc1c87acf9a8ebc17de18cb2b3cfeca547cf ]

Function pl011_throttle_rx() calls pl011_stop_rx() to disable RX, which
also disables the RX DMA by clearing the RXDMAE bit of the DMACR
register. However, to properly unthrottle RX when DMA is used, the
function pl011_unthrottle_rx() is expected to set the RXDMAE bit of
the DMACR register, which it currently lacks. This causes RX to stall
after the throttle API is called.

Set RXDMAE bit in the DMACR register while unthrottling RX if RX DMA is
used.

Fixes: 211565b10099 ("serial: pl011: UPSTAT_AUTORTS requires .throttle/unthrottle")
Cc: stable@vger.kernel.org
Signed-off-by: Kartik Rajput 
Reviewed-by: Linus Walleij 
Link: https://lore.kernel.org/r/20241113092629.60226-1-kkartik@nvidia.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: amba-pl011: Use port lock wrappers

2024-12-14T18:54:24+00:00

[ Upstream commit 68ca3e72d7463d79d29b6e4961d6028df2a88e25 ]

When a serial port is used for kernel console output, then all
modifications to the UART registers which are done from other contexts,
e.g. getty, termios, are interference points for the kernel console.

So far this has been ignored and the printk output is based on the
principle of hope. The rework of the console infrastructure which aims to
support threaded and atomic consoles, requires to mark sections which
modify the UART registers as unsafe. This allows the atomic write function
to make informed decisions and eventually to restore operational state. It
also allows to prevent the regular UART code from modifying UART registers
while printk output is in progress.

All modifications of UART registers are guarded by the UART port lock,
which provides an obvious synchronization point with the console
infrastructure.

To avoid adding this functionality to all UART drivers, wrap the
spin_[un]lock*() invocations for uart_port::lock into helper functions
which just contain the spin_[un]lock*() invocations for now. In a
subsequent step these helpers will gain the console synchronization
mechanisms.

Converted with coccinelle. No functional change.

Signed-off-by: Thomas Gleixner 
Signed-off-by: John Ogness 
Link: https://lore.kernel.org/r/20230914183831.587273-18-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman 
Stable-dep-of: 2bcacc1c87ac ("serial: amba-pl011: Fix RX stall when DMA is used")
Signed-off-by: Sasha Levin