linux-stable.git/include/linux/serial_8250.h, branch v4.14.331

Revert "8250: add support for ASIX devices with a FIFO bug"

2023-08-11T09:33:46+00:00

commit a82d62f708545d22859584e0e0620da8e3759bbc upstream.

This reverts commit eb26dfe8aa7eeb5a5aa0b7574550125f8aa4c3b3.

Commit eb26dfe8aa7e ("8250: add support for ASIX devices with a FIFO
bug") merged on Jul 13, 2012 adds a quirk for PCI_VENDOR_ID_ASIX
(0x9710). But that ID is the same as PCI_VENDOR_ID_NETMOS defined in
1f8b061050c7 ("[PATCH] Netmos parallel/serial/combo support") merged
on Mar 28, 2005. In pci_serial_quirks array, the NetMos entry always
takes precedence over the ASIX entry even since it was initially
merged, code in that commit is always unreachable.

In my tests, adding the FIFO workaround to pci_netmos_init() makes no
difference, and the vendor driver also does not have such workaround.
Given that the code was never used for over a decade, it's safe to
revert it.

Also, the real PCI_VENDOR_ID_ASIX should be 0x125b, which is used on
their newer AX99100 PCIe serial controllers released on 2016. The FIFO
workaround should not be intended for these newer controllers, and it
was never implemented in vendor driver.

Fixes: eb26dfe8aa7e ("8250: add support for ASIX devices with a FIFO bug")
Cc: stable 
Signed-off-by: Jiaqing Zhao 
Reviewed-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/20230619155743.827859-1-jiaqing.zhao@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

serial: 8250: Rate limit serial port rx interrupts during input overruns

2019-12-05T14:37:26+00:00

[ Upstream commit 6d7f677a2afa1c82d7fc7af7f9159cbffd5dc010 ]

When a serial port gets faulty or gets flooded with inputs, its interrupt
handler starts to work double time to get the characters to the workqueue
for the tty layer to handle them. When this busy time on the serial/tty
subsystem happens during boot, where it is also busy on the userspace
trying to initialise, some processes can continuously get preempted
and will be on hold until the interrupts subside.

The fix is to backoff on processing received characters for a specified
amount of time when an input overrun is seen (received a new character
before the previous one is processed). This only stops receive and will
continue to transmit characters to serial port. After the backoff period
is done, it receive will be re-enabled. This is optional and will only
be enabled by setting 'overrun-throttle-ms' in the dts.

Signed-off-by: Darwin Dingel 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: 8250: Use hrtimers for rs485 delays

2017-08-28T18:51:20+00:00

Previously the timers where based on the classic timers, giving a too
coarse resolution on systems with configs of less than 1000 HZ.

This patch changes the rs485 timers to hrtimers.

Signed-off-by: Rafael Gago Castano 
Signed-off-by: Greg Kroah-Hartman

serial: 8250: Expose set_ldisc function

2016-11-16T09:59:38+00:00

Expose set_ldisc() function so that it can be overridden with a
platform specific implementation.

Signed-off-by: Ed Blake 
Signed-off-by: Greg Kroah-Hartman

serial: 8250: Add IrDA to UART capabilities

2016-11-16T09:59:38+00:00

Add an IrDA UART capability flag and change the type of
uart_8250_port.capabilities to be u32 rather than unsigned short to
accommodate the additional flag.

Signed-off-by: Ed Blake 
Signed-off-by: Greg Kroah-Hartman

Revert "tty/serial/8250: use mctrl_gpio helpers"

2016-08-31T13:36:01+00:00

Serial console is broken in v4.8-rcX. Mika and I independently bisected down to
commit 4ef03d328769 ("tty/serial/8250: use mctrl_gpio helpers").

Since neither author nor anyone else didn't propose a solution we better revert
it for now.

This reverts commit 4ef03d328769eddbfeca1f1c958fdb181a69c341.

Link: https://lkml.kernel.org/r/20160809130229.GN1729@lahna.fi.intel.com
Signed-off-by: Andy Shevchenko 
Tested-by: Heikki Krogerus 
Tested-by: Mika Westerberg 
Signed-off-by: Greg Kroah-Hartman

tty/serial/8250: use mctrl_gpio helpers

2016-06-25T21:30:42+00:00

This patch permits the usage for GPIOs to control
the CTS/RTS/DTR/DSR/DCD/RI signals.

Signed-off-by: Yegor Yefremov 
Signed-off-by: Greg Kroah-Hartman

serial: 8250: export get_mctrl function

2016-04-30T16:26:55+00:00

Exposes get_mctrl() function so that it can be overriden with platform
specific implementation.

Signed-off-by: Wan Ahmad Zainie 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Heikki Krogerus 
Signed-off-by: Greg Kroah-Hartman

tty: Add software emulated RS485 support for 8250

2016-02-07T06:23:26+00:00

Implementation of software emulation of RS485 direction handling is based
on omap_serial driver.
Before and after transmission RTS is set to the appropriate value.

Note that before calling serial8250_em485_init() the caller has to
ensure that UART will interrupt when shift register empty. Otherwise,
emultaion cannot be used.

Both serial8250_em485_init() and serial8250_em485_destroy() are
idempotent functions.

Signed-off-by: Matwey V. Kornilov 
Signed-off-by: Greg Kroah-Hartman

tty/early: make serial8250_early_{in,out} static again

2015-07-24T00:43:30+00:00

Commit ed71871bed719 ("tty/8250_early: Turn serial_in/serial_out into
weak symbols") made these routines weak to allow platform specific
Big endian override

However recent updates to core, specifically ebc5e20082 ("serial:
of_serial: Support big-endian register accesses") and 6e63be3fee14
("serial: earlycon: Add support for big-endian MMIO accesses") means
that round about way to overide the early serial accessors is no longer
needed.

Cc: Jiri Slaby 
Cc: Peter Hurley 
Cc: Rob Herring 
Cc: Kevin Cernekee 
Acked-by: Noam Camus 
Signed-off-by: Vineet Gupta 
Reviewed-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman