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: 9ee4b83e51 ("serial: 8250: Add support for dmaengine")
Cc: stable <stable@kernel.org>
Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
Link: https://lore.kernel.org/r/20250208124148.1189191-1-jkeeping@inmusicbrands.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Implement the necessary callbacks to switch the 8250 console driver
to perform as an nbcon console.
Add implementations for the nbcon console callbacks:
->write_atomic()
->write_thread()
->device_lock()
->device_unlock()
and add CON_NBCON to the initial @flags.
All register access in the callbacks are within unsafe sections.
The ->write_atomic() and ->write_thread() callbacks allow safe
handover/takeover per byte and add a preceding newline if they
take over from another context mid-line.
For the ->write_atomic() callback, a new irq_work is used to defer
modem control since it may be called from a context that does not
allow waking up tasks.
Note: A new __serial8250_clear_IER() is introduced for direct
clearing of UART_IER. This will allow to restore the lockdep
check to serial8250_clear_IER() in a follow-up commit.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20250107212702.169493-6-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
For RS485 mode, if SER_RS485_RX_DURING_TX is not available, the
console ->write() callback needs to enable/disable Tx. It does
this by calling the ->rs485_start_tx() and ->rs485_stop_tx()
callbacks. However, some of these callbacks also disable/enable
interrupts and makes power management calls. This causes 2
problems for console writing:
1. A console write can occur in contexts that are illegal for
pm_runtime_*(). It is not even necessary for console writing
to use pm_runtime_*() because a console already does this in
serial8250_console_setup() and serial8250_console_exit().
2. The console ->write() callback already handles
disabling/enabling the interrupts by properly restoring the
previous IER value.
Add an argument @toggle_ier to the ->rs485_start_tx() and
->rs485_stop_tx() callbacks to specify if they may disable/enable
receive interrupts while using pm_runtime_*(). Console writing
will not allow the toggling.
For all call sites other than console writing there is no
functional change.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20250107212702.169493-5-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently serial8250_console_fifo_write() directly writes into
the UART_TX register rather than using the high-level function
serial8250_console_putchar(). This is because
serial8250_console_putchar() waits for the holding register to
become empty, which would defeat the purpose of the FIFO code.
Move the LSR_THRE waiting to a new function
serial8250_console_wait_putchar() so that the FIFO code can use
serial8250_console_putchar(). This will be particularly important
for a follow-up commit, where output bytes are inspected to track
newlines.
This is only refactoring and has no functional change.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20250107212702.169493-4-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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: 8f3631f0f6 ("serial/8250: Use fifo in 8250 console driver")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Wander Lairson Costa <wander@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20250107212702.169493-2-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The commit f9b11229b7 ("serial: 8250: Fix PM usage_count for console
handover") fixed one runtime PM usage counter balance problem that
occurs because .dev is not set during univ8250 setup preventing call to
pm_runtime_get_sync(). Later, univ8250_console_exit() will trigger the
runtime PM usage counter underflow as .dev is already set at that time.
Call pm_runtime_get_sync() to balance the RPM usage counter also in
serial8250_register_8250_port() before trying to add the port.
Reported-by: Borislav Petkov (AMD) <bp@alien8.de>
Fixes: bedb404e91 ("serial: 8250_port: Don't use power management for kernel console")
Cc: stable <stable@kernel.org>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20241210170120.2231-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The CREAD feature of termios is implemented by setting/clearing
UART_LSR_DR within @ignore_status_mask. For this feature to
function correctly, it requires that UART_LSR_DR is never
masked (unset) in @read_status_mask so that uart_insert_char()
can properly drop the character if CREAD is disabled.
Currently there are code paths that clear/set UART_LSR_DR from
@read_status_mask at times. This appears to be a relic from
Linux 1.1.60, where @read_status_mask could be used to mask
all UART_LSR reading. However, since Linux 2.1.8 that is no
longer the case. Now if UART_LSR_DR is cleared from
@read_status_mask, received characters may not be dropped
even though CREAD is disabled.
This can be seen when:
- CREAD is disabled (UART_LSR_DR is set in @ignore_status_mask)
- LSR has an error bit set from UART_LSR_BRK_ERROR_BITS
(and that error is not ignored via @ignore_status_mask)
- UART_LSR_DR is cleared in @read_status_mask
In this case characters will be inserted into the tty buffer
even though they should be ignored.
Remove all setting/clearing of UART_LSR_DR for
@read_status_mask except for its initialization.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20241216171244.12783-4-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since Linux 2.1.8 @read_status_mask is no longer used as a
general control of which bits are used from the LSR register.
Instead it has become an additional mask applied to
@ignore_status_mask. Since UART_LSR_THRE is never set for
@ignore_status_mask, it serves no purpose to set it for
@read_status_mask. In fact, it propagates the misconception
that @read_status_mask can be used as a general mask for LSR
bits.
Do not set UART_LSR_THRE for @read_status_mask.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20241216171244.12783-3-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit f19c3f6c81 ("serial: 8250_port: Don't service RX FIFO if
throttled") uses @read_status_mask (bit UART_LSR_DR) to determine
if Rx has been stopped. However, the bit UART_LSR_DR is not
managed properly in @read_status_mask for all Rx stop/start
situations and is therefore not suitable for this purpose.
Use the UART_IER_RLSI and UART_IER_RDI bits in @ier instead, as
this is already common in 8250-variants and drivers.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20241216171244.12783-2-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In the B0 revision, the RTS pin remains high due to incorrect hardware
mapping. To address this issue, enable auto-direction control with the
RTS bit in ADCL_CFG_REG. This configuration ensures that the RTS pin
goes low when the terminal is opened and high when the terminal is
closed. Additionally, we reset the step counter for Rx and Tx engines
by writing into FRAC_DIV_CFG_REG.
Signed-off-by: Rengarajan S <rengarajan.s@microchip.com>
Link: https://lore.kernel.org/r/20241218094017.18290-1-rengarajan.s@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 7c7e6c8924 ("tty: serial: handle HAS_IOPORT dependencies")
triggers warning backtraces on a number of platforms which don't support
IO ports.
WARNING: CPU: 0 PID: 0 at drivers/tty/serial/8250/8250_port.c:470 serial8250_set_defaults+0x148/0x1d8
Unsupported UART type 0
The problem is seen because serial8250_set_defaults() is called for
all members of the serial8250_ports[] array even if that array is
not initialized.
Work around the problem by only displaying the warning if the port
type is not 0 (UPIO_PORT) or if iobase is set for the port.
Fixes: 7c7e6c8924 ("tty: serial: handle HAS_IOPORT dependencies")
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Stafford Horne <shorne@gmail.com>
Link: https://lore.kernel.org/r/20241205143033.2695333-1-linux@roeck-us.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull tty / serial driver updates from Greg KH:
"Here is a small set of tty and serial driver updates for 6.13-rc1.
Nothing major at all this time, only some small changes:
- few device tree binding updates
- 8250_exar serial driver updates
- imx serial driver updates
- sprd_serial driver updates
- other tiny serial driver updates, full details in the shortlog
All of these have been in linux-next for a while with one reported
issue, but that commit has now been reverted"
* tag 'tty-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (37 commits)
Revert "serial: sh-sci: Clean sci_ports[0] after at earlycon exit"
serial: amba-pl011: fix build regression
dt-bindings: serial: Add a new compatible string for ums9632
serial: sprd: Add support for sc9632
tty/serial/altera_uart: unwrap error log string
tty/serial/altera_jtaguart: unwrap error log string
serial: amba-pl011: Fix RX stall when DMA is used
tty: ldsic: fix tty_ldisc_autoload sysctl's proc_handler
serial: 8250_fintek: Add support for F81216E
serial: sh-sci: Clean sci_ports[0] after at earlycon exit
tty: atmel_serial: Fix typo retreives to retrieves
tty: atmel_serial: Use devm_platform_ioremap_resource()
serial: 8250: omap: Move pm_runtime_get_sync
tty: serial: samsung: Add Exynos8895 compatible
dt-bindings: serial: samsung: Add samsung,exynos8895-uart compatible
serial: 8250_dw: Add Sophgo SG2044 quirk
dt-bindings: serial: snps-dw-apb-uart: Add Sophgo SG2044 uarts
dt-bindings: serial: snps,dw-apb-uart: merge duplicate compatible entry.
altera_jtaguart: Use dev_err() to report error attaching IRQ
altera_uart: Use dev_err() to report error attaching IRQ handler
...
Pull asm-generic updates from Arnd Bergmann:
"These are a number of unrelated cleanups, generally simplifying the
architecture specific header files:
- A series from Al Viro simplifies asm/vga.h, after it turns out that
most of it can be generalized.
- A series from Julian Vetter adds a common version of
memcpy_{to,from}io() and memset_io() and changes most architectures
to use that instead of their own implementation
- A series from Niklas Schnelle concludes his work to make PC style
inb()/outb() optional
- Nicolas Pitre contributes improvements for the generic do_div()
helper
- Christoph Hellwig adds a generic version of page_to_phys() and
phys_to_page(), replacing the slightly different architecture
specific definitions.
- Uwe Kleine-Koenig has a minor cleanup for ioctl definitions"
* tag 'asm-generic-3.13' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: (24 commits)
empty include/asm-generic/vga.h
sparc: get rid of asm/vga.h
asm/vga.h: don't bother with scr_mem{cpy,move}v() unless we need to
vt_buffer.h: get rid of dead code in default scr_...() instances
tty: serial: export serial_8250_warn_need_ioport
lib/iomem_copy: fix kerneldoc format style
hexagon: simplify asm/io.h for !HAS_IOPORT
loongarch: Use new fallback IO memcpy/memset
csky: Use new fallback IO memcpy/memset
arm64: Use new fallback IO memcpy/memset
New implementation for IO memcpy and IO memset
watchdog: Add HAS_IOPORT dependency for SBC8360 and SBC7240
__arch_xprod64(): make __always_inline when optimizing for performance
ARM: div64: improve __arch_xprod_64()
asm-generic/div64: optimize/simplify __div64_const32()
lib/math/test_div64: add some edge cases relevant to __div64_const32()
asm-generic: add an optional pfn_valid check to page_to_phys
asm-generic: provide generic page_to_phys and phys_to_page implementations
asm-generic/io.h: Remove I/O port accessors for HAS_IOPORT=n
tty: serial: handle HAS_IOPORT dependencies
...
Currently in omap_8250_shutdown, the dma->rx_running flag is
set to zero in omap_8250_rx_dma_flush. Next pm_runtime_get_sync
is called, which is a runtime resume call stack which can
re-set the flag. When the call omap_8250_shutdown returns, the
flag is expected to be UN-SET, but this is not the case. This
is causing issues the next time UART is re-opened and
omap_8250_rx_dma is called. Fix by moving pm_runtime_get_sync
before the omap_8250_rx_dma_flush.
cc: stable@vger.kernel.org
Fixes: 0e31c8d173 ("tty: serial: 8250_omap: add custom DMA-RX callback")
Signed-off-by: Bin Liu <b-liu@ti.com>
[Judith: Add commit message]
Signed-off-by: Judith Mendez <jm@ti.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20241031172315.453750-1-jm@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The newly added function is used from a loadable module, so it has
to be exported the same way as the other function in this file:
ERROR: modpost: "serial_8250_warn_need_ioport" [drivers/tty/serial/8250/8250_pci.ko] undefined!
Fixes: 7c7e6c8924 ("tty: serial: handle HAS_IOPORT dependencies")
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
In a future patch HAS_IOPORT=n will disable inb()/outb() and friends at
compile time. We thus need to add HAS_IOPORT as dependency for those
drivers using them unconditionally. Some 8250 serial drivers support
MMIO only use, so fence only the parts requiring I/O ports and print an
error message if a device can't be supported with the current
configuration.
Co-developed-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
After commit 0edb555a65 ("platform: Make platform_driver::remove()
return void") .remove() is (again) the right callback to implement for
platform drivers.
Convert all platform drivers below drivers/tty/serial to use .remove(),
with the eventual goal to drop struct platform_driver::remove_new(). As
.remove() and .remove_new() have the same prototypes, conversion is done
by just changing the structure member name in the driver initializer.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20241007205803.444994-7-u.kleine-koenig@baylibre.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull tty / serial driver updates from Greg KH:
"Here is the "big" set of tty/serial driver updates for 6.12-rc1.
Nothing major in here, just nice forward progress in the slow cleanup
of the serial apis, and lots of other driver updates and fixes.
Included in here are:
- serial api updates from Jiri to make things more uniform and sane
- 8250_platform driver cleanups
- samsung serial driver fixes and updates
- qcom-geni serial driver fixes from Johan for the bizarre UART
engine that that chip seems to have. Hopefully it's in a better
state now, but hardware designers still seem to come up with more
ways to make broken UARTS 40+ years after this all should have
finished.
- sc16is7xx driver updates
- omap 8250 driver updates
- 8250_bcm2835aux driver updates
- a few new serial driver bindings added
- other serial minor driver updates
All of these have been in linux-next for a long time with no reported
problems"
* tag 'tty-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (65 commits)
tty: serial: samsung: Fix serial rx on Apple A7-A9
tty: serial: samsung: Fix A7-A11 serial earlycon SError
tty: serial: samsung: Use bit manipulation macros for APPLE_S5L_*
tty: rp2: Fix reset with non forgiving PCIe host bridges
serial: 8250_aspeed_vuart: Enable module autoloading
serial: qcom-geni: fix polled console corruption
serial: qcom-geni: disable interrupts during console writes
serial: qcom-geni: fix console corruption
serial: qcom-geni: introduce qcom_geni_serial_poll_bitfield()
serial: qcom-geni: fix arg types for qcom_geni_serial_poll_bit()
soc: qcom: geni-se: add GP_LENGTH/IRQ_EN_SET/IRQ_EN_CLEAR registers
serial: qcom-geni: fix false console tx restart
serial: qcom-geni: fix fifo polling timeout
tty: hvc: convert comma to semicolon
mxser: convert comma to semicolon
serial: 8250_bcm2835aux: Fix clock imbalance in PM resume
serial: sc16is7xx: convert bitmask definitions to use BIT() macro
serial: sc16is7xx: fix copy-paste errors in EFR_SWFLOWx_BIT constants
serial: sc16is7xx: remove SC16IS7XX_MSR_DELTA_MASK
serial: xilinx_uartps: Make cdns_rs485_supported static
...
