AuxXxilium/linux_dsm_epyc7002
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424d79183a
linux_dsm_epyc7002/drivers/tty/serial
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Douglas Anderson 424d79183a serial: 8250_dw: Avoid "too much work" from bogus rx timeout interrupt 
On a Rockchip rk3399-based board during suspend/resume testing, we
found that we could get the console UART into a state where it would
print this to the console a lot:
  serial8250: too much work for irq42

Followed eventually by:
  NMI watchdog: BUG: soft lockup - CPU#0 stuck for 11s!

Upon debugging I found that we're in this state:
  iir = 0x000000cc
  lsr = 0x00000060

It appears that somehow we have a RX Timeout interrupt but there is no
actual data present to receive.  When we're in this state the UART
driver claims that it handled the interrupt but it actually doesn't
really do anything.  This means that we keep getting the interrupt
over and over again.

Normally we don't actually need to do anything special to handle a RX
Timeout interrupt.  We'll notice that there is some data ready and
we'll read it, which will end up clearing the RX Timeout.  In this
case we have a problem specifically because we got the RX TImeout
without any data.  Reading a bogus byte is confirmed to get us out of
this state.

It's unclear how exactly the UART got into this state, but it is known
that the UART lines are essentially undriven and unpowered during
suspend, so possibly during resume some garbage / half transmitted
bits are seen on the line and put the UART into this state.

The UART on the rk3399 is a DesignWare based 8250 UART.  From mailing
list posts, it appears that other people have run into similar
problems with DesignWare based IP.  Presumably this problem is unique
to that IP, so I have placed the workaround there to avoid possibly of
accidentally triggering bad behavior on other IP.  Also note the RX
Timeout behaves very differently in the DMA case, for for now the
workaround is only applied to the non-DMA case.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-02-10 15:10:16 +01:00
..
8250 serial: 8250_dw: Avoid "too much work" from bogus rx timeout interrupt 2017-02-10 15:10:16 +01:00
cpm_uart tty: serial: cpm_uart: make use of for_each_node_by_type() 2017-02-03 10:12:16 +01:00
jsm tty: serial: jsm_tty: constify uart_ops structures 2016-09-02 15:01:16 +02:00
21285.c
altera_jtaguart.c serial: altera: constify uart_ops structures 2016-09-02 15:01:16 +02:00
altera_uart.c serial: altera: constify uart_ops structures 2016-09-02 15:01:16 +02:00
amba-pl010.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
amba-pl011.c tty: serial: pl011: add ttyAMA for matching pl011 console 2017-02-03 10:12:16 +01:00
amba-pl011.h tty: amba-pl011: clean up LCR register offsets 2015-12-13 19:59:48 -08:00
apbuart.c tty: serial: apbuart: Fix module autoload for OF platform driver 2015-10-04 19:09:21 +01:00
apbuart.h
ar933x_uart.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
arc_uart.c serial/arc: constify uart_ops structures 2016-09-01 21:05:41 +02:00
atmel_serial.c tty/serial: atmel: RS485 half duplex w/DMA: enable RX after TX is done 2017-01-11 08:18:45 +01:00
bcm63xx_uart.c serial/bcm63xx_uart: constify uart_ops structures 2016-09-02 15:01:16 +02:00
bfin_sport_uart.c tty: serial: constify dev_pm_ops structures 2017-01-19 14:20:23 +01:00
bfin_sport_uart.h
bfin_uart.c serial:bfin-uart:Remove 'struct timeval' 2015-12-13 19:59:48 -08:00
clps711x.c serial: clps711x: Changing the compatibility string to match with the smallest supported chip 2016-07-06 17:38:16 +02:00
crisv10.c serial: crisv10: fix invalid user-pointer check 2016-11-10 14:41:25 +01:00
crisv10.h
digicolor-usart.c tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE 2016-02-14 17:39:36 -08:00
dz.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
dz.h
earlycon-arm-semihost.c tty/serial: mark __init early_smh_setup() static 2016-09-02 15:03:35 +02:00
earlycon.c ACPI: parse SPCR and enable matching console 2016-09-28 17:46:46 +02:00
efm32-uart.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
etraxfs-uart.c serial: etraxfs-uart: Fix crash 2015-11-20 16:19:54 -08:00
fsl_lpuart.c tty: serial: fsl_lpuart: fix del_timer_sync() vs timer routine deadlock 2017-01-12 11:51:24 +01:00
icom.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
icom.h
ifx6x60.c serial: ifx6x60: Free memory when probe fails 2016-11-10 14:50:46 +01:00
ifx6x60.h
imx.c serial: imx: Fix the CTS_B polarity in RS485 mode 2017-01-31 10:54:58 +01:00
ioc3_serial.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
ioc4_serial.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
ip22zilog.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
ip22zilog.h
Kconfig tty: serial: lantiq: implement earlycon support 2017-01-12 11:51:24 +01:00
kgdb_nmi.c
kgdboc.c
lantiq.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
lpc32xx_hs.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
m32r_sio_reg.h
m32r_sio.c serial: m32r_sio: make it explicitly non-modular 2016-06-25 14:00:06 -07:00
Makefile tty: serial: Makefile: move kgdb to be initialized last 2016-10-27 16:27:24 +02:00
max310x.c serial: max310x: Add support for newer silicon revisions 2017-01-12 11:51:24 +01:00
max3100.c tty: serial: constify uart_ops structures 2016-09-02 15:01:16 +02:00
mcf.c
men_z135_uart.c tty: serial: constify uart_ops structures 2016-09-02 15:01:16 +02:00
meson_uart.c tty: serial: meson: allow baud-rates higher than 115200 2017-01-19 14:38:57 +01:00
mpc52xx_uart.c tty: serial: constify psc_ops structs 2016-02-06 22:31:47 -08:00
mps2-uart.c serial: mps2-uart: make driver explicitly non-modular 2016-06-25 14:01:57 -07:00
mpsc.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
msm_serial.c tty: serial: msm: Fix module autoload 2017-01-12 11:51:25 +01:00
mux.c parisc: serial/mux: Convert to uart_console_device instead of open-coded 2015-10-22 15:44:28 +02:00
mvebu-uart.c serial: mvebu-uart: free the IRQ in ->shutdown() 2016-06-25 14:00:06 -07:00
mxs-auart.c serial: mxs-auart: support CMSPAR termios cflag 2017-01-12 11:51:24 +01:00
netx-serial.c
omap-serial.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
pch_uart.c serial: pch_uart: add terminate entry for dmi_system_id tables 2016-10-27 16:01:31 +02:00
pic32_uart.c serial: pic32_uart: Fix 'request_irq' and 'free_irq' inconsistancy 2017-01-12 11:51:24 +01:00
pic32_uart.h serial: pic32_uart: Add PIC32 UART driver 2016-05-13 14:01:56 +02:00
pmac_zilog.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
pmac_zilog.h
pnx8xxx_uart.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
pxa.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
rp2.c
sa1100.c
samsung.c serial: samsung: enable clock before accessing interrupt mask resister 2017-02-03 10:12:16 +01:00
samsung.h serial: samsung: Simplify DMA engine initialization code 2017-01-12 11:51:24 +01:00
sb1250-duart.c
sc16is7xx.c Merge 4.9-rc3 into tty-next 2016-10-30 06:42:10 -04:00
sccnxp.c
serial_core.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
serial_ks8695.c serial: Fix ASYNC_* => UPF_* flags misuse 2016-01-28 14:17:42 -08:00
serial_mctrl_gpio.c serial: mctrl_gpio: enable API usage only for initialized mctrl_gpios struct 2016-06-25 14:30:42 -07:00
serial_mctrl_gpio.h serial: mctrl_gpio: add modem control read routine 2016-06-25 14:30:42 -07:00
serial_txx9.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
serial-tegra.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
sh-sci.c serial: sh-sci: make RX FIFO parameters tunable via sysfs 2017-02-06 09:47:52 +01:00
sh-sci.h serial: sh-sci: consider DR (data ready) bit adequately 2017-02-03 10:14:10 +01:00
sirfsoc_uart.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
sirfsoc_uart.h serial: sirf: make fifo functions static 2016-06-25 14:01:57 -07:00
sn_console.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
sprd_serial.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
st-asc.c serial: st-asc: Use generic DT binding for announcing RTS/CTS lines 2017-02-06 09:47:52 +01:00
stm32-usart.c serial: stm32: mark symbols static where possible 2016-09-27 12:55:27 +02:00
stm32-usart.h serial: stm32: Fix comparisons with undefined register 2016-10-27 16:00:31 +02:00
suncore.c drivers/tty: make serial/suncore.c driver explicitly non-modular 2015-07-23 18:27:41 -07:00
sunhv.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
sunsab.c
sunsab.h
sunsu.c serial: sunsu: Free memory when probe fails 2016-11-16 10:57:26 +01:00
sunzilog.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
sunzilog.h
tilegx.c
timbuart.c tty: serial: constify uart_ops structures 2016-09-02 15:01:16 +02:00
timbuart.h
uartlite.c serial-uartlite: constify uart_ops structures 2016-09-02 15:01:16 +02:00
ucc_uart.c QE-UART: add "fsl,t1040-ucc-uart" to of_device_id 2016-05-01 13:55:12 -07:00
vr41xx_siu.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
vt8500_serial.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
xilinx_uartps.c serial: xuartps: Enable uart loopback mode 2017-01-25 11:08:30 +01:00
zs.c tty: serial: constify uart_ops structures 2017-01-27 09:23:36 +01:00
zs.h