linux_dsm_epyc7002/drivers
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
..
accessibility
acpi Merge branches 'acpi-scan', 'acpi-sysfs', 'acpi-wdat' and 'acpi-tables' 2017-01-06 14:36:30 +01:00
amba
android
ata Merge branch 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata 2016-12-13 15:30:50 -08:00
atm Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
auxdisplay auxdisplay: fix new ht16k33 build errors 2017-01-11 09:27:30 +01:00
base Revert "driver core: Add deferred_probe attribute to devices in sysfs" 2017-01-14 14:09:03 +01:00
bcma
block Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-01-14 17:07:04 -08:00
bluetooth Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-16 10:24:44 -08:00
bus cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
cdrom Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
char serdev: Introduce new bus for serial attached devices 2017-02-03 10:17:02 +01:00
clk One fix for a broken driver on Renesas RZ/A1 SoCs with bootloaders that don't 2017-01-06 15:35:27 -08:00
clocksource Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
connector
cpufreq Merge branch 'pm-cpufreq' 2017-01-06 14:34:52 +01:00
cpuidle Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-12-27 17:51:36 -08:00
dax libnvdimm for 4.10 2016-12-18 15:49:10 -08:00
dca
devfreq PM / devfreq: exynos-bus: Fix the wrong return value 2017-01-03 00:21:45 +01:00
dio Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
dma serial: 8250_mid: handle interrupt correctly in DMA case 2017-01-19 14:20:23 +01:00
dma-buf
edac Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
eisa
extcon extcon: return error code on failure 2017-01-11 09:11:39 +01:00
firewire
firmware Merge branch 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-01-15 10:54:39 -08:00
fmc
fpga
gpio gpio: Move freeing of GPIO hogs before numbing of the device 2016-12-30 09:11:21 +01:00
gpu Merge branch 'drm-fixes-4.10' of git://people.freedesktop.org/~agd5f/linux into drm-fixes 2017-01-09 09:47:19 +10:00
hid HID: i2c-hid: Add sleep between POWER ON and RESET 2017-01-11 21:55:35 +01:00
hsi
hv clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
hwmon hwmon: (lm90) fix temp1_max_alarm attribute 2017-01-02 10:15:28 -08:00
hwspinlock
hwtracing coresight/etm3/4x: Consolidate hotplug state space 2016-12-25 10:47:44 +01:00
i2c i2c: piix4: Avoid race conditions with IMC 2017-01-12 20:52:12 +01:00
ide Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
idle Power management material for v4.10-rc1 2016-12-13 10:41:53 -08:00
iio First round of IIO fixes for the 4.10 cycle. 2017-01-02 16:59:44 +01:00
infiniband net/mlx4_core: Fix raw qp flow steering rules under SRIOV 2016-12-29 14:17:40 -05:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2017-01-13 11:49:34 -08:00
iommu IOMMU Fixes for Linux v4.10-rc2 2017-01-06 10:49:36 -08:00
ipack
irqchip Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
isdn Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
leds cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
lguest Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
lightnvm Char/Misc driver patches for 4.10-rc1 2016-12-13 12:11:01 -08:00
macintosh Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mailbox ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
mcb
md md/raid5: Use correct IS_ERR() variation on pointer check 2017-01-09 13:58:10 -08:00
media ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
memory
memstick Merge branch 'for-4.10/block' of git://git.kernel.dk/linux-block 2016-12-13 10:19:16 -08:00
message Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mfd - New Device Support 2016-12-19 08:16:26 -08:00
misc mei: bus: enable OS version only for SPT and newer 2017-01-11 07:43:57 +01:00
mmc Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mtd Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
net Merge branch 'akpm' (patches from Andrew) 2017-01-11 11:15:15 -08:00
nfc
ntb ntb_transport: Remove unnecessary call to ntb_peer_spad_read 2016-12-23 16:11:07 -05:00
nubus Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
nvdimm libnvdimm for 4.10 2016-12-18 15:49:10 -08:00
nvme nvme: use blk_rq_payload_bytes 2017-01-13 15:17:04 -07:00
nvmem nvmem: fix nvmem_cell_read() return type doc 2017-01-04 18:22:47 +01:00
of pci-v4.10-changes 2016-12-15 12:46:48 -08:00
oprofile Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
parisc Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
parport Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
pci ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
pcmcia drivers/pcmcia/m32r_pcc.c: check return from add_pcc_socket 2016-12-12 18:55:06 -08:00
perf cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
phy SCSI misc on 20161213 2016-12-14 10:49:33 -08:00
pinctrl pinctrl: samsung: Fix the width of PINCFG_TYPE_DRV bitfields for Exynos5433 2016-12-30 14:27:42 +01:00
platform platform/x86: fujitsu-laptop: use brightness_set_blocking for LED-setting callbacks 2016-12-28 12:38:10 +02:00
pnp Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
power ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
powercap
pps
ps3
ptp Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-12 19:56:15 -08:00
pwm pwm: Changes for v4.10-rc1 2016-12-15 11:45:13 -08:00
rapidio
ras
regulator - New Device Support 2016-12-19 08:16:26 -08:00
remoteproc Revert "remoteproc: Merge table_ptr and cached_table pointers" 2016-12-30 03:26:31 -08:00
reset ARM: SoC driver updates for v4.10 2016-12-15 16:03:25 -08:00
rpmsg rpmsg: virtio_rpmsg_bus: fix channel creation 2016-12-30 03:12:11 -08:00
rtc ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
s390 ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
sbus Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
scsi Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-01-14 17:07:04 -08:00
sfi
sh lib: radix-tree: check accounting of existing slot replacement users 2016-12-12 18:55:08 -08:00
sn
soc powerpc updates for 4.10 2016-12-16 09:26:42 -08:00
spi dmaengine updates for 4.10-rc1 2016-12-14 20:42:45 -08:00
spmi
ssb
staging staging: octeon: Call SET_NETDEV_DEV() 2017-01-03 17:11:50 +01:00
target target: support XCOPY requests without parameters 2017-01-10 08:41:30 -08:00
tc
thermal Power management material for v4.10-rc1 2016-12-13 10:41:53 -08:00
thunderbolt Char/Misc driver patches for 4.10-rc1 2016-12-13 12:11:01 -08:00
tty serial: 8250_dw: Avoid "too much work" from bogus rx timeout interrupt 2017-02-10 15:10:16 +01:00
uio uio-hv-generic: store physical addresses instead of virtual 2016-12-10 14:57:58 +01:00
usb USB-serial fixes for v4.10-rc4 2017-01-12 18:17:38 +01:00
uwb
vfio vfio/type1: Remove pid_namespace.h include 2017-01-13 08:23:33 -07:00
vhost Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-16 10:24:44 -08:00
video console: Make persistent scrollback a boot parameter 2017-01-25 11:54:02 +01:00
virt
virtio virtio_mmio: Set dev.release() to avoid warning 2016-12-16 00:13:39 +02:00
vlynq
vme vme: Fix wrong pointer utilization in ca91cx42_slave_get 2017-01-11 10:42:16 +01:00
w1
watchdog Watchdog updates for v4.10 2016-12-24 11:27:45 -08:00
xen Merge branch 'stable/for-linus-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb 2017-01-06 10:53:21 -08:00
zorro Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
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