linux-stable/drivers/tty/serial
Johan Hovold c0a6c9f79e serial: msm_serial: drop low-latency workaround
Commit f77232dab2 ("tty: serial: msm: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.

Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.

The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.

Since commit a9c3f68f3c ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.

Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-17-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-04-22 12:09:25 +02:00
..
8250 serial: do not restore interrupt state in sysrq helper 2021-04-22 12:04:26 +02:00
cpm_uart tty: cpm_uart, use port->flags instead of low_latency 2021-01-07 16:17:31 +01:00
jsm Merge 5.12-rc6 into tty-next 2021-04-05 08:59:21 +02:00
21285.c tty: serial: 21285: fix lockup on open 2020-10-28 13:39:14 +01:00
altera_jtaguart.c serial: altera_jtaguart: drop low-latency workaround 2021-04-22 12:09:24 +02:00
altera_uart.c serial: altera_uart: drop low-latency workaround 2021-04-22 12:09:24 +02:00
amba-pl010.c serial: amba-pl010: drop low-latency workaround 2021-04-22 12:09:24 +02:00
amba-pl011.c serial: amba-pl011: drop low-latency workaround 2021-04-22 12:09:24 +02:00
amba-pl011.h
apbuart.c serial: apbuart: drop low-latency workaround 2021-04-22 12:09:25 +02:00
apbuart.h
ar933x_uart.c serial: ar933x: drop low-latency workaround 2021-04-22 12:09:25 +02:00
arc_uart.c serial: arc_uart: drop low-latency workaround 2021-04-22 12:09:25 +02:00
atmel_serial.c serial: atmel_serial: drop low-latency workaround 2021-04-22 12:09:25 +02:00
atmel_serial.h
bcm63xx_uart.c serial: bcm63xx: drop low-latency workaround 2021-04-22 12:09:25 +02:00
clps711x.c
digicolor-usart.c
dz.c
dz.h
earlycon-arm-semihost.c
earlycon-riscv-sbi.c
earlycon.c earlycon: simplify earlycon-table implementation 2020-12-04 15:49:48 +01:00
fsl_linflexuart.c tty: serial: linflexuart: Remove unnecessary '|' operation and add error count 2020-11-06 17:12:30 +01:00
fsl_lpuart.c serial: fsl_lpuart: Use of_device_get_match_data() 2021-01-20 18:48:15 +01:00
icom.c serial: icom: drop low-latency workaround 2021-04-22 12:09:25 +02:00
icom.h
imx.c serial: imx: drop workaround for forced irq threading 2021-03-23 10:32:44 +01:00
imx_earlycon.c tty: serial: imx: add imx earlycon driver 2020-07-29 17:11:02 +02:00
ip22zilog.c
ip22zilog.h
Kconfig tty: serial: samsung_tty: Add support for Apple UARTs 2021-03-10 09:34:10 +01:00
kgdb_nmi.c tty: do not check tty_unregister_driver's return value 2021-03-10 09:34:09 +01:00
kgdboc.c
lantiq.c tty/serial/lantiq: convert comma to semicolon 2020-12-28 16:10:50 +01:00
liteuart.c serial: liteuart: fix return value check in liteuart_probe() 2021-03-10 09:34:10 +01:00
lpc32xx_hs.c serial: lpc32xx_hs: drop low-latency workaround 2021-04-22 12:09:25 +02:00
Makefile serial: ifx6x60: Remove driver for deprecated platform 2021-01-26 19:21:49 +01:00
max310x.c tty: max310x: fix flexible_array.cocci warnings 2021-03-23 10:24:27 +01:00
max3100.c tty_port: drop last traces of low_latency 2021-01-07 16:17:32 +01:00
mcf.c serial: mcf: drop low-latency workaround 2021-04-22 12:09:25 +02:00
men_z135_uart.c tty: serial, fix kernel-doc 2020-08-18 13:51:18 +02:00
meson_uart.c serial: meson: drop low-latency workaround 2021-04-22 12:09:25 +02:00
milbeaut_usio.c
mpc52xx_uart.c serial: mpc52xx_uart: drop low-latency workaround 2021-04-22 12:09:25 +02:00
mps2-uart.c
msm_serial.c serial: msm_serial: drop low-latency workaround 2021-04-22 12:09:25 +02:00
mux.c
mvebu-uart.c serial: mvebu-uart: fix tx lost characters at power off 2020-12-28 16:17:34 +01:00
mxs-auart.c serial: mxs-auart: Remove <asm/cacheflush.h> 2021-01-20 18:48:19 +01:00
omap-serial.c serial: omap: fix rs485 half-duplex filtering 2021-04-22 12:07:07 +02:00
owl-uart.c tty: serial: owl: Add support for kernel debugger 2021-01-13 17:16:54 +01:00
pch_uart.c serial: pch_uart: fix build error with !CONFIG_DEBUG_FS 2021-03-23 10:31:09 +01:00
pic32_uart.c
pic32_uart.h
pmac_zilog.c m68k: Fix WARNING splat in pmac_zilog driver 2020-11-23 11:31:00 +01:00
pmac_zilog.h tty: serial: pmac_zilog: Remove unused disposable variable 'garbage' 2020-11-13 15:28:27 +01:00
pxa.c
qcom_geni_serial.c serial: do not restore interrupt state in sysrq helper 2021-04-22 12:04:26 +02:00
rda-uart.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
rp2.c
sa1100.c serial: sa1100: use platform_get_resource() 2020-08-18 15:02:06 +02:00
samsung_tty.c tty: serial: samsung_tty: remove spinlock flags in interrupt handlers 2021-03-23 10:20:38 +01:00
sb1250-duart.c MIPS: Replace SIBYTE_1956_WAR by CONFIG_SB1_PASS_2_WORKAROUNDS 2020-09-07 22:24:51 +02:00
sc16is7xx.c sc16is7xx: Defer probe if device read fails 2021-04-05 12:07:32 +02:00
sccnxp.c
serial-tegra.c tty: serial: serial-tegra: Provide some missing struct member descriptions 2020-11-06 10:54:05 +01:00
serial_core.c serial: core: return early on unsupported ioctls 2021-04-10 10:36:34 +02:00
serial_mctrl_gpio.c serial: mctrl_gpio: Fix passing zero to 'ERR_PTR' warning 2020-11-06 17:12:05 +01:00
serial_mctrl_gpio.h
serial_txx9.c serial: txx9: add missing platform_driver_unregister() on error in serial_txx9_init 2020-11-06 17:24:41 +01:00
sh-sci.c serial: sh-sci: remove obsolete latency workaround 2021-04-15 12:59:16 +02:00
sh-sci.h
sifive.c riscv: Fix sifive serial driver 2021-01-07 18:02:13 -08:00
sprd_serial.c
st-asc.c
stm32-usart.c serial: stm32: defer sysrq processing 2021-04-22 12:04:26 +02:00
stm32-usart.h tty/serial: Add rx-tx-swap OF option to stm32-usart 2021-04-05 12:06:52 +02:00
suncore.c
sunhv.c Revert "serial: sunhv: Initialize lock for non-registered console" 2020-07-21 18:21:49 +02:00
sunsab.c
sunsab.h
sunsu.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
sunzilog.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
sunzilog.h
tegra-tcu.c serial: Add missing MODULE_DEVICE_TABLE 2021-04-10 10:37:27 +02:00
timbuart.c tty: timbuart: convert tasklets to use new tasklet_setup() API 2020-08-18 13:33:13 +02:00
timbuart.h
uartlite.c tty: serial: uartlite: Support probe deferral 2020-12-04 16:51:40 +01:00
ucc_uart.c serial: ucc_uart: make qe_uart_set_mctrl() static 2020-09-16 13:14:58 +02:00
vr41xx_siu.c
vt8500_serial.c
xilinx_uartps.c tty: serial: xilinx_uartps: Supply description for missing member 'cts_override' 2020-11-06 10:54:05 +01:00
zs.c
zs.h