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f6aa5beb45
linux/drivers/tty/serial
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Marek Vasut f6aa5beb45 serial: 8250: Fix clearing FIFOs in RS485 mode again 
The 8250 FIFOs indeed need to be cleared after stopping transmission in
RS485 mode without SER_RS485_RX_DURING_TX flag set. But there are two
problems with the approach taken by the previous patch from Fixes tag.

First, serial8250_clear_fifos() should clear fifos, but what it really
does is it enables the FIFOs unconditionally if present, clears them
and then sets the FCR register to zero, which effectively disables the
FIFOs. In case the FIFO is disabled, enabling it and clearing it makes
no sense and in fact can trigger misbehavior of the 8250 core. Moreover,
the FCR register may contain other FIFO configuration bits which may not
be writable unconditionally and writing them incorrectly can trigger
misbehavior of the 8250 core too. (ie. AM335x UART swallows the first
byte and retransmits the last byte twice because of this FCR write).

Second, serial8250_clear_and_reinit_fifos() completely reloads the FCR,
but what really has to happen at the end of the RS485 transmission is
clearing of the FIFOs and nothing else.

This patch repairs serial8250_clear_fifos() so that it really only
clears the FIFOs by operating on FCR[2:1] bits and leaves all the
other bits alone. It also undoes serial8250_clear_and_reinit_fifos()
from __do_stop_tx_rs485() as serial8250_clear_fifos() is sufficient.

Signed-off-by: Marek Vasut <marex@denx.de>
Fixes: 2bed8a8e70 ("Clearing FIFOs in RS485 emulation mode causes subsequent transmits to break")
Cc: Daniel Jedrychowski <avistel@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable <stable@vger.kernel.org> # let it bake a bit before merging
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-09-18 16:07:25 +02:00
..
8250 serial: 8250: Fix clearing FIFOs in RS485 mode again 2018-09-18 16:07:25 +02:00
cpm_uart tty: Convert to using %pOFn instead of device_node.name 2018-09-18 16:07:25 +02:00
jsm tty: serial: jsm: remove redundant pointer ch 2018-07-13 15:36:32 +02:00
21285.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
altera_jtaguart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
altera_uart.c serial: altera: set RRDY flag also without irq 2018-02-28 13:30:09 +01:00
amba-pl010.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
amba-pl011.c tty: pl011: Avoid spuriously stuck-off interrupts 2018-05-14 13:41:05 +02:00
amba-pl011.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
apbuart.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
apbuart.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ar933x_uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
arc_uart.c serial: arc_uart: Fix out-of-bounds access through DT alias 2018-02-28 15:29:59 +01:00
atmel_serial.c tty/serial: atmel: Change the driver to work under at91-usart MFD 2018-09-10 16:12:43 +01:00
atmel_serial.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
bcm63xx_uart.c MIPS changes for 4.15 2017-11-15 11:36:08 -08:00
clps711x.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
digicolor-usart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
dz.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
dz.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
earlycon-arm-semihost.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
earlycon.c earlycon: Remove hardcoded port->uartclk initialization in of_setup_earlycon 2018-05-14 13:41:05 +02:00
efm32-uart.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
fsl_lpuart.c serial: fsl_lpuart: Fix out-of-bounds access through DT alias 2018-02-28 15:29:59 +01:00
icom.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
icom.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
ifx6x60.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
ifx6x60.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
imx.c tty: serial: imx: add pinctrl sleep/default mode switch for suspend 2018-09-18 16:07:24 +02:00
ioc3_serial.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
ioc4_serial.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
ip22zilog.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
ip22zilog.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig tty/serial: atmel: Change the driver to work under at91-usart MFD 2018-09-10 16:12:43 +01:00
kgdb_nmi.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
kgdboc.c kgdboc: Fix restrict error 2018-09-18 16:07:23 +02:00
lantiq.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
lpc32xx_hs.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
Makefile TTY/Serial driver patches for 4.17-rc1 2018-04-04 18:43:49 -07:00
max310x.c serial: max310x: Check the clock readiness 2018-06-28 21:07:54 +09:00
max3100.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
mcf.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
men_z135_uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
meson_uart.c tty: serial: meson: fix typo in the "stop bit" register definition 2017-11-28 15:32:33 +01:00
mpc52xx_uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
mps2-uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
mpsc.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
msm_serial.c tty: serial: msm_serial: Add __maybe_unused to suspend/resume callbacks 2018-05-14 13:41:05 +02:00
mux.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
mvebu-uart.c Merge 4.17-rc3 into tty-next 2018-04-30 05:14:55 -07:00
mxs-auart.c serial: mxs-auart: Fix potential infinite loop 2018-09-18 16:07:24 +02:00
netx-serial.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
omap-serial.c tty: omap-serial: Fix initial on-boot RTS GPIO level 2018-01-09 16:45:17 +01:00
owl-uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
pch_uart.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
pic32_uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
pic32_uart.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
pmac_zilog.c tty: Convert to using %pOFn instead of device_node.name 2018-09-18 16:07:25 +02:00
pmac_zilog.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pnx8xxx_uart.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
pxa.c serial: pxa: Fix an error handling path in 'serial_pxa_probe()' 2018-06-28 21:07:54 +09:00
qcom_geni_serial.c tty: serial: qcom_geni_serial: Fix serial when not used as console 2018-09-18 16:07:24 +02:00
rp2.c treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
sa1100.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
samsung.c serial: samsung: Enable baud clock for UART reset procedure in resume 2018-09-18 16:07:24 +02:00
samsung.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
sb1250-duart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
sc16is7xx.c sc16is7xx: Check for an error when the clock is enabled. 2018-04-25 14:56:12 +02:00
sccnxp.c headers: separate linux/mod_devicetable.h from linux/platform_device.h 2018-07-07 17:52:26 +02:00
serial_core.c uart: fix race between uart_put_char() and uart_shutdown() 2018-07-13 11:26:43 +02:00
serial_ks8695.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
serial_mctrl_gpio.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
serial_mctrl_gpio.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
serial_txx9.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
serial-tegra.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
sh-sci.c serial: sh-sci: Add earlycon for R7S9210 2018-09-18 16:07:24 +02:00
sh-sci.h serial: sh-sci: Support for HSCIF RX sampling point adjustment 2018-04-23 10:08:18 +02:00
sirfsoc_uart.c serial: sirf: Fix out-of-bounds access through DT alias 2018-02-28 15:30:00 +01:00
sirfsoc_uart.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
sn_console.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
sprd_serial.c serial: sprd: Fix the indentation issue 2018-09-18 16:07:24 +02:00
st-asc.c tty: serial: simplify getting .drvdata 2018-04-22 17:29:43 +02:00
stm32-usart.c serial: stm32: fix initialization of RS485 mode 2018-03-15 17:39:43 +01:00
stm32-usart.h serial: stm32: add support for RS485 hardware control mode 2018-03-14 13:35:37 +01:00
suncore.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
sunhv.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
sunsab.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
sunsab.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sunsu.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
sunzilog.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
sunzilog.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
timbuart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
timbuart.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
uartlite.c tty: serial: uartlite: Use dynamic array for console port 2018-09-18 16:07:24 +02:00
ucc_uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
vr41xx_siu.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
vt8500_serial.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
xilinx_uartps.c serial: uartps: Enable automatic flow control 2018-09-18 16:07:23 +02:00
zs.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
zs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00