linux-stable.git/drivers/tty/serial, branch v6.10

serial: qcom-geni: do not kill the machine on fifo underrun

2024-07-04T10:30:30+00:00

The Qualcomm GENI serial driver did not handle buffer flushing and used
to print discarded characters when the circular buffer was cleared.
Since commit 1788cf6a91d9 ("tty: serial: switch from circ_buf to kfifo")
this instead resulted in a hard lockup due to
qcom_geni_serial_send_chunk_fifo() spinning indefinitely in the
interrupt handler.

The underlying bugs have now been fixed, but make sure to output NUL
characters instead of killing the machine if a similar driver bug is
ever reintroduced.

Signed-off-by: Johan Hovold 
Link: https://lore.kernel.org/r/20240704101805.30612-4-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman

serial: qcom-geni: fix hard lockup on buffer flush

2024-07-04T10:30:30+00:00

The Qualcomm GENI serial driver does not handle buffer flushing and used
to continue printing discarded characters when the circular buffer was
cleared. Since commit 1788cf6a91d9 ("tty: serial: switch from circ_buf
to kfifo") this instead results in a hard lockup due to
qcom_geni_serial_send_chunk_fifo() spinning indefinitely in the
interrupt handler.

This is easily triggered by interrupting a command such as dmesg in a
serial console but can also happen when stopping a serial getty on
reboot.

Implement the flush_buffer() callback and use it to cancel any active TX
command when the write buffer has been emptied.

Reported-by: Douglas Anderson 
Link: https://lore.kernel.org/lkml/20240610222515.3023730-1-dianders@chromium.org/
Fixes: 1788cf6a91d9 ("tty: serial: switch from circ_buf to kfifo")
Fixes: a1fee899e5be ("tty: serial: qcom_geni_serial: Fix softlock")
Cc: stable@vger.kernel.org	# 5.0
Signed-off-by: Johan Hovold 
Link: https://lore.kernel.org/r/20240704101805.30612-3-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman

serial: qcom-geni: fix soft lockup on sw flow control and suspend

2024-07-04T10:30:30+00:00

The stop_tx() callback is used to implement software flow control and
must not discard data as the Qualcomm GENI driver is currently doing
when there is an active TX command.

Cancelling an active command can also leave data in the hardware FIFO,
which prevents the watermark interrupt from being enabled when TX is
later restarted. This results in a soft lockup and is easily triggered
by stopping TX using software flow control in a serial console but this
can also happen after suspend.

Fix this by only stopping any active command, and effectively clearing
the hardware fifo, when shutting down the port. When TX is later
restarted, a transfer command may need to be issued to discard any stale
data that could prevent the watermark interrupt from firing.

Fixes: c4f528795d1a ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Cc: stable@vger.kernel.org	# 4.17
Signed-off-by: Johan Hovold 
Link: https://lore.kernel.org/r/20240704101805.30612-2-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman

serial: imx: ensure RTS signal is not left active after shutdown

2024-07-03T14:12:49+00:00

If a process is killed while writing to a /dev/ttymxc* device in RS485
mode, we observe that the RTS signal is left high, thus making it
impossible for other devices to transmit anything.

Moreover, the ->tx_state variable is left in state SEND, which means
that when one next opens the device and configures baud rate etc., the
initialization code in imx_uart_set_termios dutifully ensures the RTS
pin is pulled down, but since ->tx_state is already SEND, the logic in
imx_uart_start_tx() does not in fact pull the pin high before
transmitting, so nothing actually gets on the wire on the other side
of the transceiver. Only when that transmission is allowed to complete
is the state machine then back in a consistent state.

This is completely reproducible by doing something as simple as

  seq 10000 > /dev/ttymxc0

and hitting ctrl-C, and watching with a logic analyzer.

Signed-off-by: Rasmus Villemoes 
Cc: stable 
Reviewed-by: Marek Vasut 
Link: https://lore.kernel.org/r/20240625184206.508837-1-linux@rasmusvillemoes.dk
Signed-off-by: Greg Kroah-Hartman

tty: serial: ma35d1: Add a NULL check for of_node

2024-07-03T14:12:06+00:00

The pdev->dev.of_node can be NULL if the "serial" node is absent.
Add a NULL check to return an error in such cases.

Fixes: 930cbf92db01 ("tty: serial: Add Nuvoton ma35d1 serial driver support")
Reported-by: Dan Carpenter 
Closes: https://lore.kernel.org/all/8df7ce45-fd58-4235-88f7-43fe7cd67e8f@moroto.mountain/
Signed-off-by: Jacky Huang 
Reviewed-by: Dan Carpenter 
Cc: stable 
Link: https://lore.kernel.org/r/20240625064128.127-1-ychuang570808@gmail.com
Signed-off-by: Greg Kroah-Hartman

serial: 8250_omap: Fix Errata i2310 with RX FIFO level check

2024-07-03T14:10:57+00:00

Errata i2310[0] says, Erroneous timeout can be triggered,
if this Erroneous interrupt is not cleared then it may leads
to storm of interrupts.

Commit 9d141c1e6157 ("serial: 8250_omap: Implementation of Errata i2310")
which added the workaround but missed ensuring RX FIFO is really empty
before applying the errata workaround as recommended in the errata text.
Fix this by adding back check for UART_OMAP_RX_LVL to be 0 for
workaround to take effect.

[0] https://www.ti.com/lit/pdf/sprz536 page 23

Fixes: 9d141c1e6157 ("serial: 8250_omap: Implementation of Errata i2310")
Cc: stable@vger.kernel.org
Reported-by: Vignesh Raghavendra 
Closes: https://lore.kernel.org/all/e96d0c55-0b12-4cbf-9d23-48963543de49@ti.com/
Signed-off-by: Udit Kumar 
Link: https://lore.kernel.org/r/20240625160725.2102194-1-u-kumar1@ti.com
Signed-off-by: Greg Kroah-Hartman

serial: imx: only set receiver level if it is zero

2024-07-03T13:55:03+00:00

With commit a81dbd0463ec ("serial: imx: set receiver level before
starting uart") we set the receiver level to its default value. This
caused a regression when using SDMA, where the receiver level is 9
instead of 8 (default). This change will first check if the receiver
level is zero and only then set it to the default. This still avoids the
interrupt storm when the receiver level is zero.

Fixes: a81dbd0463ec ("serial: imx: set receiver level before starting uart")
Cc: stable 
Signed-off-by: Stefan Eichenberger 
Link: https://lore.kernel.org/r/20240703112543.148304-1-eichest@gmail.com
Signed-off-by: Greg Kroah-Hartman

Revert "serial: core: Add support for DEVNAME:0.0 style naming for kernel console"

2024-06-25T05:58:00+00:00

This reverts commit 787a1cabac01c99846070fcf702e53befaf89f79.

Let's roll back all of the serial core and printk console changes that
went into 6.10-rc1 as there still are problems with them that need to be
sorted out.

Link: https://lore.kernel.org/r/ZnpRozsdw6zbjqze@tlindgre-MOBL1
Reported-by: Petr Mladek 
Reported-by: Tony Lindgren 
Cc: Jiri Slaby 
Cc: John Ogness 
Cc: Sergey Senozhatsky 
Cc: Andy Shevchenko 
Cc: Ilpo Järvinen 
Signed-off-by: Greg Kroah-Hartman

Revert "serial: core: Handle serial console options"

2024-06-25T05:57:58+00:00

This reverts commit a0f32e2dd99867b164bfebcf36729c2a0d41b30b.

Let's roll back all of the serial core and printk console changes that
went into 6.10-rc1 as there still are problems with them that need to be
sorted out.

Link: https://lore.kernel.org/r/ZnpRozsdw6zbjqze@tlindgre-MOBL1
Reported-by: Petr Mladek 
Reported-by: Tony Lindgren 
Cc: Jiri Slaby 
Cc: John Ogness 
Cc: Sergey Senozhatsky 
Cc: Andy Shevchenko 
Cc: Ilpo Järvinen 
Signed-off-by: Greg Kroah-Hartman

Revert "serial: 8250: Add preferred console in serial8250_isa_init_ports()"

2024-06-25T05:57:55+00:00

This reverts commit a8b04cfe7dad84e65df5996e14b435fd356fe62c.

Let's roll back all of the serial core and printk console changes that
went into 6.10-rc1 as there still are problems with them that need to be
sorted out.

Link: https://lore.kernel.org/r/ZnpRozsdw6zbjqze@tlindgre-MOBL1
Reported-by: Petr Mladek 
Reported-by: Tony Lindgren 
Cc: Jiri Slaby 
Cc: John Ogness 
Cc: Sergey Senozhatsky 
Cc: Andy Shevchenko 
Cc: Ilpo Järvinen 
Signed-off-by: Greg Kroah-Hartman