In RS485 mode, the RTS pin is driven high by hardware when the transmitter
is operating. This behaviour cannot be changed. This means that the driver
should claim that it supports SER_RS485_RTS_ON_SEND and not
SER_RS485_RTS_AFTER_SEND.
Otherwise, when configuring the port with the SER_RS485_RTS_ON_SEND, one
get the following warning:
kern.warning kernel: atmel_usart_serial atmel_usart_serial.2.auto:
ttyS1 (1): invalid RTS setting, using RTS_AFTER_SEND instead
which is contradictory with what's really happening.
Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>
Cc: stable <stable@kernel.org>
Tested-by: Alexander Dahl <ada@thorsis.com>
Fixes: af47c491e3 ("serial: atmel: Fill in rs485_supported")
Link: https://lore.kernel.org/r/20240808060637.19886-1-othacehe@gnu.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 6e20753da6 ("tty: vt: conmakehash: cope with abs_srctree no
longer in env") included <linux/limits.h>, which invoked another
(wrong) patch that tried to address a build error on macOS.
According to the specification [1], the correct header to use PATH_MAX
is <limits.h>.
The minimal fix would be to replace <linux/limits.h> with <limits.h>.
However, the following commits seem questionable to me:
- 3bd85c6c97 ("tty: vt: conmakehash: Don't mention the full path of the input in output")
- 6e20753da6 ("tty: vt: conmakehash: cope with abs_srctree no longer in env")
These commits made too many efforts to cope with a comment header in
drivers/tty/vt/consolemap_deftbl.c:
/*
* Do not edit this file; it was automatically generated by
*
* conmakehash drivers/tty/vt/cp437.uni > [this file]
*
*/
With this commit, the header part of the generate C file will be
simplified as follows:
/*
* Automatically generated file; Do not edit.
*/
BTW, another series of excessive efforts for a comment header can be
seen in the following:
- 5ef6dc08cf ("lib/build_OID_registry: don't mention the full path of the script in output")
- 2fe29fe945 ("lib/build_OID_registry: avoid non-destructive substitution for Perl < 5.13.2 compat")
[1]: https://pubs.opengroup.org/onlinepubs/009695399/basedefs/limits.h.html
Fixes: 6e20753da6 ("tty: vt: conmakehash: cope with abs_srctree no longer in env")
Cc: stable <stable@kernel.org>
Reported-by: Daniel Gomez <da.gomez@samsung.com>
Closes: https://lore.kernel.org/all/20240807-macos-build-support-v1-11-4cd1ded85694@samsung.com/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240809160853.1269466-1-masahiroy@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
With "earlycon initcall_debug=1 loglevel=8" in bootargs, kernel
sometimes boot hang. It is because normal console still is not ready,
but runtime suspend is called, so early console putchar will hang
in waiting TRDE set in UARTSTAT.
The lpuart driver has auto suspend delay set to 3000ms, but during
uart_add_one_port, a child device serial ctrl will added and probed with
its pm runtime enabled(see serial_ctrl.c).
The runtime suspend call path is:
device_add
|-> bus_probe_device
|->device_initial_probe
|->__device_attach
|-> pm_runtime_get_sync(dev->parent);
|-> pm_request_idle(dev);
|-> pm_runtime_put(dev->parent);
So in the end, before normal console ready, the lpuart get runtime
suspended. And earlycon putchar will hang.
To address the issue, mark last busy just after pm_runtime_enable,
three seconds is long enough to switch from bootconsole to normal
console.
Fixes: 43543e6f53 ("tty: serial: fsl_lpuart: Add runtime pm support")
Cc: stable <stable@kernel.org>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20240808140325.580105-1-peng.fan@oss.nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit af224ca2df (serial: core: Prevent unsafe uart port access, part
3) added few uport == NULL checks. It added one to uart_shutdown(), so
the commit assumes, uport can be NULL in there. But right after that
protection, there is an unprotected "uart_port_dtr_rts(uport, false);"
call. That is invoked only if HUPCL is set, so I assume that is the
reason why we do not see lots of these reports.
Or it cannot be NULL at this point at all for some reason :P.
Until the above is investigated, stay on the safe side and move this
dereference to the if too.
I got this inconsistency from Coverity under CID 1585130. Thanks.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240805102046.307511-3-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use of_property_present() to test for property presence rather than
of_get_property(). This is part of a larger effort to remove callers
of of_get_property() and similar functions. of_get_property() leaks
the DT property data pointer which is a problem for dynamically
allocated nodes which may be freed.
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20240731191312.1710417-17-robh@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The first element in uart_8250_port is a structure, so initializing
it to 0 causes a warning on newer compilers:
drivers/tty/serial/8250/8250_platform.c: In function 'serial8250_platform_probe':
drivers/tty/serial/8250/8250_platform.c:111:40: error: excess elements in struct initializer [-Werror]
111 | struct uart_8250_port uart = { 0 };
Use the modern empty {} initializer instead that works on all
supported compilers.
Fixes: d9e5a0ce2f ("serial: 8250_platform: Enable generic 16550A platform devices")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20240807075751.2206508-2-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The acpi_platform_serial_table[] array is defined globally without
an #ifdef check for CONFIG_ACPI, so ACPI_PTR() makes no sense
here:
drivers/tty/serial/8250/8250_platform.c:271:36: error: 'acpi_platform_serial_table' defined but not used [-Werror=unused-const-variable=]
271 | static const struct acpi_device_id acpi_platform_serial_table[] = {
Fixes: d9e5a0ce2f ("serial: 8250_platform: Enable generic 16550A platform devices")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Link: https://lore.kernel.org/r/20240807075751.2206508-1-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, 8250_platform driver is used only for devices with fixed
serial ports (plat_serial8250_port). Extend this driver for any generic
16550A platform devices which can be probed using standard hardware
discovery mechanisms like ACPI.
This is required in particular for RISC-V which has non-PNP generic
16550A compatible UART that needs to be enumerated as ACPI platform
device.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Link: https://lore.kernel.org/r/20240730051218.767580-1-sunilvl@ventanamicro.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are two other drivers that bind to "mrvl,mmp-uart": the 8250_of
and the 8250_pxa. The previous one is generic and the latter is binded
to ARCH_PXA || ARCH_MMP. Now we may have pxa programming compatible
HW to support, making use of the generic 8250_of seems a good idea.
However, there's no earlycon support if we go with this solution. So
move the mmp|pxa-uart earlycon code to core 8250_early.c.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20240711160720.3488-2-jszhang@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Previously 8250_dma used a circular xmit->buf as DMA output buffer. This
causes messages that wrap around in the circular buffer to be
transmitted using 2 DMA transfers. Depending on baud rate and processor
load this can cause an interchar gap in the middle of the message. On
the receiving end the gap may cause a short receive timeout, possibly
long enough to terminate a DMA transfer, but too short to restart a
receive DMA transfer in time thus causing a receive buffer overrun.
This is especially a problem for devices with high speed UARTs (HSU)
where even deep 64 byte FIFO's are not sufficient to handle interrupt
latency.
The circular buffer has now been replaced by kfifo which requires a SG
list with a single entry, which still causes 2 dma transfers when a wrap
around occurs. Fix this by allowing up to 2 entries in the sgl.
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Ferry Toth <ftoth@exalondelft.nl>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20240716214055.102269-1-ftoth@exalondelft.nl
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When enabling access to the special register set, Receiver time-out and
RHR interrupts can happen. In this case, the IRQ handler will try to read
from the FIFO thru the RHR register at address 0x00, but address 0x00 is
mapped to DLL register, resulting in erroneous FIFO reading.
Call graph example:
sc16is7xx_startup(): entry
sc16is7xx_ms_proc(): entry
sc16is7xx_set_termios(): entry
sc16is7xx_set_baud(): DLH/DLL = $009C --> access special register set
sc16is7xx_port_irq() entry --> IIR is 0x0C
sc16is7xx_handle_rx() entry
sc16is7xx_fifo_read(): --> unable to access FIFO (RHR) because it is
mapped to DLL (LCR=LCR_CONF_MODE_A)
sc16is7xx_set_baud(): exit --> Restore access to general register set
Fix the problem by claiming the efr_lock mutex when accessing the Special
register set.
Fixes: dfeae619d7 ("serial: sc16is7xx")
Cc: stable@vger.kernel.org
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20240723125302.1305372-3-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Sometimes, when a packet is received on channel A at almost the same time
as a packet is about to be transmitted on channel B, we observe with a
logic analyzer that the received packet on channel A is transmitted on
channel B. In other words, the Tx buffer data on channel B is corrupted
with data from channel A.
The problem appeared since commit 4409df5866 ("serial: sc16is7xx: change
EFR lock to operate on each channels"), which changed the EFR locking to
operate on each channel instead of chip-wise.
This commit has introduced a regression, because the EFR lock is used not
only to protect the EFR registers access, but also, in a very obscure and
undocumented way, to protect access to the data buffer, which is shared by
the Tx and Rx handlers, but also by each channel of the IC.
Fix this regression first by switching to kfifo_out_linear_ptr() in
sc16is7xx_handle_tx() to eliminate the need for a shared Rx/Tx buffer.
Secondly, replace the chip-wise Rx buffer with a separate Rx buffer for
each channel.
Fixes: 4409df5866 ("serial: sc16is7xx: change EFR lock to operate on each channels")
Cc: stable@vger.kernel.org
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20240723125302.1305372-2-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Calling ioctl TIOCSSERIAL with an invalid baud_base can
result in uartclk being zero, which will result in a
divide by zero error in uart_get_divisor(). The check for
uartclk being zero in uart_set_info() needs to be done
before other settings are made as subsequent calls to
ioctl TIOCSSERIAL for the same port would be impacted if
the uartclk check was done where uartclk gets set.
Oops: divide error: 0000 PREEMPT SMP KASAN PTI
RIP: 0010:uart_get_divisor (drivers/tty/serial/serial_core.c:580)
Call Trace:
<TASK>
serial8250_get_divisor (drivers/tty/serial/8250/8250_port.c:2576
drivers/tty/serial/8250/8250_port.c:2589)
serial8250_do_set_termios (drivers/tty/serial/8250/8250_port.c:502
drivers/tty/serial/8250/8250_port.c:2741)
serial8250_set_termios (drivers/tty/serial/8250/8250_port.c:2862)
uart_change_line_settings (./include/linux/spinlock.h:376
./include/linux/serial_core.h:608 drivers/tty/serial/serial_core.c:222)
uart_port_startup (drivers/tty/serial/serial_core.c:342)
uart_startup (drivers/tty/serial/serial_core.c:368)
uart_set_info (drivers/tty/serial/serial_core.c:1034)
uart_set_info_user (drivers/tty/serial/serial_core.c:1059)
tty_set_serial (drivers/tty/tty_io.c:2637)
tty_ioctl (drivers/tty/tty_io.c:2647 drivers/tty/tty_io.c:2791)
__x64_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:907
fs/ioctl.c:893 fs/ioctl.c:893)
do_syscall_64 (arch/x86/entry/common.c:52
(discriminator 1) arch/x86/entry/common.c:83 (discriminator 1))
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
Reported-by: syzkaller <syzkaller@googlegroups.com>
Cc: stable@vger.kernel.org
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
Rule: add
Link: https://lore.kernel.org/stable/1721148848-9784-1-git-send-email-george.kennedy%40oracle.com
Link: https://lore.kernel.org/r/1721219078-3209-1-git-send-email-george.kennedy@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull more devicetree updates from Rob Herring:
"Most of this is a treewide change to of_property_for_each_u32() which
was small enough to do in one go before rc1 and avoids the need to
create of_property_for_each_u32_some_new_name().
- Treewide conversion of of_property_for_each_u32() to drop internal
arguments making struct property opaque
- Add binding for Amlogic A4 SoC watchdog
- Fix constraints for AD7192 'single-channel' property"
* tag 'devicetree-fixes-for-6.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
dt-bindings: iio: adc: ad7192: Fix 'single-channel' constraints
of: remove internal arguments from of_property_for_each_u32()
dt-bindings: watchdog: add support for Amlogic A4 SoCs
Pull printk updates from Petr Mladek:
- trivial printk changes
The bigger "real" printk work is still being discussed.
* tag 'printk-for-6.11-trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
vsprintf: add missing MODULE_DESCRIPTION() macro
printk: Rename console_replay_all() and update context
Pull driver core updates from Greg KH:
"Here is the big set of driver core changes for 6.11-rc1.
Lots of stuff in here, with not a huge diffstat, but apis are evolving
which required lots of files to be touched. Highlights of the changes
in here are:
- platform remove callback api final fixups (Uwe took many releases
to get here, finally!)
- Rust bindings for basic firmware apis and initial driver-core
interactions.
It's not all that useful for a "write a whole driver in rust" type
of thing, but the firmware bindings do help out the phy rust
drivers, and the driver core bindings give a solid base on which
others can start their work.
There is still a long way to go here before we have a multitude of
rust drivers being added, but it's a great first step.
- driver core const api changes.
This reached across all bus types, and there are some fix-ups for
some not-common bus types that linux-next and 0-day testing shook
out.
This work is being done to help make the rust bindings more safe,
as well as the C code, moving toward the end-goal of allowing us to
put driver structures into read-only memory. We aren't there yet,
but are getting closer.
- minor devres cleanups and fixes found by code inspection
- arch_topology minor changes
- other minor driver core cleanups
All of these have been in linux-next for a very long time with no
reported problems"
* tag 'driver-core-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (55 commits)
ARM: sa1100: make match function take a const pointer
sysfs/cpu: Make crash_hotplug attribute world-readable
dio: Have dio_bus_match() callback take a const *
zorro: make match function take a const pointer
driver core: module: make module_[add|remove]_driver take a const *
driver core: make driver_find_device() take a const *
driver core: make driver_[create|remove]_file take a const *
firmware_loader: fix soundness issue in `request_internal`
firmware_loader: annotate doctests as `no_run`
devres: Correct code style for functions that return a pointer type
devres: Initialize an uninitialized struct member
devres: Fix memory leakage caused by driver API devm_free_percpu()
devres: Fix devm_krealloc() wasting memory
driver core: platform: Switch to use kmemdup_array()
driver core: have match() callback in struct bus_type take a const *
MAINTAINERS: add Rust device abstractions to DRIVER CORE
device: rust: improve safety comments
MAINTAINERS: add Danilo as FIRMWARE LOADER maintainer
MAINTAINERS: add Rust FW abstractions to FIRMWARE LOADER
firmware: rust: improve safety comments
...
The of_property_for_each_u32() macro needs five parameters, two of which
are primarily meant as internal variables for the macro itself (in the
for() clause). Yet these two parameters are used by a few drivers, and this
can be considered misuse or at least bad practice.
Now that the kernel uses C11 to build, these two parameters can be avoided
by declaring them internally, thus changing this pattern:
struct property *prop;
const __be32 *p;
u32 val;
of_property_for_each_u32(np, "xyz", prop, p, val) { ... }
to this:
u32 val;
of_property_for_each_u32(np, "xyz", val) { ... }
However two variables cannot be declared in the for clause even with C11,
so declare one struct that contain the two variables we actually need. As
the variables inside this struct are not meant to be used by users of this
macro, give the struct instance the noticeable name "_it" so it is visible
during code reviews, helping to avoid new code to use it directly.
Most usages are trivially converted as they do not use those two
parameters, as expected. The non-trivial cases are:
- drivers/clk/clk.c, of_clk_get_parent_name(): easily doable anyway
- drivers/clk/clk-si5351.c, si5351_dt_parse(): this is more complex as the
checks had to be replicated in a different way, making code more verbose
and somewhat uglier, but I refrained from a full rework to keep as much
of the original code untouched having no hardware to test my changes
All the changes have been build tested. The few for which I have the
hardware have been runtime-tested too.
Reviewed-by: Andre Przywara <andre.przywara@arm.com> # drivers/clk/sunxi/clk-simple-gates.c, drivers/clk/sunxi/clk-sun8i-bus-gates.c
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> # drivers/gpio/gpio-brcmstb.c
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com> # drivers/irqchip/irq-atmel-aic-common.c
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> # drivers/iio/adc/ti_am335x_adc.c
Acked-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com> # drivers/pwm/pwm-samsung.c
Acked-by: Richard Leitner <richard.leitner@linux.dev> # drivers/usb/misc/usb251xb.c
Acked-by: Mark Brown <broonie@kernel.org> # sound/soc/codecs/arizona.c
Reviewed-by: Richard Fitzgerald <rf@opensource.cirrus.com> # sound/soc/codecs/arizona.c
Acked-by: Michael Ellerman <mpe@ellerman.id.au> # arch/powerpc/sysdev/xive/spapr.c
Acked-by: Stephen Boyd <sboyd@kernel.org> # clk
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Acked-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20240724-of_property_for_each_u32-v3-1-bea82ce429e2@bootlin.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Pull tty / serial updates from Greg KH:
"Here is a small set of tty and serial driver updates for 6.11-rc1. Not
much happened this cycle, unlike the previous kernel release which had
lots of "excitement" in this part of the kernel. Included in here are
the following changes:
- dt binding updates for new platforms
- 8250 driver updates
- various small serial driver fixes and updates
- printk/console naming and matching attempt #2 (was reverted for
6.10-final, should be good to go this time around, acked by the
relevant maintainers).
All of these have been in linux-next for a while with no reported
issues"
* tag 'tty-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (22 commits)
Documentation: kernel-parameters: Add DEVNAME:0.0 format for serial ports
serial: core: Add serial_base_match_and_update_preferred_console()
printk: Add match_devname_and_update_preferred_console()
serial: sc16is7xx: hardware reset chip if reset-gpios is defined in DT
dt-bindings: serial: sc16is7xx: add reset-gpios
dt-bindings: serial: vt8500-uart: convert to json-schema
serial: 8250_platform: Explicitly show we initialise ISA ports only once
tty: add missing MODULE_DESCRIPTION() macros
dt-bindings: serial: mediatek,uart: add MT7988
serial: sh-sci: Add support for RZ/V2H(P) SoC
dt-bindings: serial: Add documentation for Renesas RZ/V2H(P) (R9A09G057) SCIF support
dt-bindings: serial: renesas,scif: Make 'interrupt-names' property as required
dt-bindings: serial: renesas,scif: Validate 'interrupts' and 'interrupt-names'
dt-bindings: serial: renesas,scif: Move ref for serial.yaml at the end
riscv: dts: starfive: jh7110: Add the core reset and jh7110 compatible for uarts
serial: 8250_dw: Use reset array API to get resets
dt-bindings: serial: snps-dw-apb-uart: Add one more reset signal for StarFive JH7110 SoC
serial: 8250: Extract platform driver
serial: 8250: Extract RSA bits
serial: imx: stop casting struct uart_port to struct imx_port
...
The Qualcomm GENI serial driver did not handle buffer flushing and used
to print discarded characters when the circular buffer was cleared.
Since commit 1788cf6a91 ("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 <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240704101805.30612-4-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 1788cf6a91 ("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 <dianders@chromium.org>
Link: https://lore.kernel.org/lkml/20240610222515.3023730-1-dianders@chromium.org/
Fixes: 1788cf6a91 ("tty: serial: switch from circ_buf to kfifo")
Fixes: a1fee899e5 ("tty: serial: qcom_geni_serial: Fix softlock")
Cc: stable@vger.kernel.org # 5.0
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240704101805.30612-3-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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: c4f528795d ("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 <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240704101805.30612-2-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 <linux@rasmusvillemoes.dk>
Cc: stable <stable@kernel.org>
Reviewed-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20240625184206.508837-1-linux@rasmusvillemoes.dk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
