linux-kernel - Re: [RFT PATCH v7 9/9] watchdog: dw_wdt: Convert to use watchdog infrastructure

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Date:	Fri, 29 Jan 2016 09:52:29 -0800
From:	Doug Anderson <dianders@...omium.org>
To:	Guenter Roeck <patchwork@...chwork.roeck-us.net>
Cc:	"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
	Wim Van Sebroeck <wim@...ana.be>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Timo Kokkonen <timo.kokkonen@...code.fi>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	Jonathan Corbet <corbet@....net>,
	Guenter Roeck <linux@...ck-us.net>
Subject: Re: [RFT PATCH v7 9/9] watchdog: dw_wdt: Convert to use watchdog infrastructure

Guenter,

On Mon, Jan 25, 2016 at 6:53 PM, Guenter Roeck
<patchwork@...chwork.roeck-us.net> wrote:
> From: Guenter Roeck <linux@...ck-us.net>
>
> Convert driver to use watchdog infrastructure. This includes
> infrastructure support to handle watchdog keepalive if the watchdog
> is running while the watchdog device is closed.
>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
>
> ---
> v7: Set max_hw_timeout_ms
>     Rebased to v4.5-rc1
> v6: Added patch
> ---
>  drivers/watchdog/Kconfig  |   1 +
>  drivers/watchdog/dw_wdt.c | 323 +++++++++++++++++-----------------------------
>  2 files changed, 117 insertions(+), 207 deletions(-)

I used the following test environment:
* Rockchip rk3288-based Chromebook
* v4.4-based kernel (specifically commit b1ba57898bfc
("veyron_defconfig: update for 4.5-rc") from Heiko Stuebner "somewhat
stable" development tree
* Pulled in some USB-related fixes (just for my own testing)
* Pulled in Wim's most recent pull request for watchdog subsystem
(ac36856fe432 watchdog: asm9260: remove __init and __exit annotations)
* Applied all 9 of your patches
* Test with daisydog
<https://chromium.googlesource.com/chromiumos/third_party/daisydog/>


I did these tests:

###
# Confirm normal functionality
###

stop daisydog
daisydog -c
# HW watchdog interval is 43 seconds
# /dev/watchdog reported boot status: normal-boot

cat /dev/watchdog
# cat: [ 5401.044582] watchdog watchdog0: watchdog did not stop!
# /dev/watchdog: Invalid argument

for i in $(seq 60); do
   echo $i
   sleep 1
 done
# 1 - 43 printed, then reboot

###
# Try setting interval, confirm all good (no reboots)
# ...then confirm that reboot happens in 10 sec
###

stop daisydog
daisydog -c
# HW watchdog interval is 43 seconds
# /dev/watchdog reported boot status: normal-boot

daisydog -i 10
# HW watchdog interval is 10 seconds
# /dev/watchdog reported boot status: normal-boot

<Ctrl-C>

daisydog -c
# HW watchdog interval is 10 seconds
# /dev/watchdog reported boot status: normal-boot

sleep 60
# No reboots

cat /dev/watchdog
# cat: [ 5401.044582] watchdog watchdog0: watchdog did not stop!
# /dev/watchdog: Invalid argument

for i in $(seq 60); do
   echo $i
   sleep 1
 done
# 1 - 11 printed, then reboot

###
# Try setting interval super long
# (outside of hardware range)
###

stop daisydog
daisydog -i 100 -c
# HW watchdog interval is 86 seconds
# /dev/watchdog reported boot status: normal-boot

cat /dev/watchdog
# cat: [ 5401.044582] watchdog watchdog0: watchdog did not stop!
# /dev/watchdog: Invalid argument

for i in $(seq 200); do
   echo $i
   sleep 1
 done
# 1 - 87 printed, then reboot; seems right to me.

###
# Try with a interval that's in hardware range, but above default
###

stop daisydog
daisydog -i 70 -c
# HW watchdog interval is 86 seconds
# /dev/watchdog reported boot status: normal-boot

cat /dev/watchdog
# cat: [ 5401.044582] watchdog watchdog0: watchdog did not stop!
# /dev/watchdog: Invalid argument

for i in $(seq 200); do
   echo $i
   sleep 1
 done
# 1 - 87 printed, then reboot; seems right to me

###
# Make sure my previous fix not regressed:
# 04b1a62e6bb9 ("watchdog: dw_wdt: keepalive the watchdog at write time")
###

stop daisydog
while true; do daisydog -c > /dev/null; done

# Let the above run for a 2 minutes and see no reboot.

###
# See what happens when you change things midway
###

stop daisydog
daisydog -c
# HW watchdog interval is 43 seconds
# /dev/watchdog reported boot status: normal-boot

cat /dev/watchdog
# cat: [ 5401.044582] watchdog watchdog0: watchdog did not stop!
# /dev/watchdog: Invalid argument

for i in $(seq 30); do
   echo $i
   sleep 1
 done
# 1 - 30 printed

daisydog -c -i 10
# HW watchdog interval is 10 seconds
# /dev/watchdog reported boot status: normal-boot

sleep 60
# No reboot; right since the "-c -i 10" patted + closed properly

===

I also tried the new functionality enabled by your new patch and added
"timeout-sec = <10>" to my device tree.  That seemed to work.  Upon
bootup the watchdog defaulted to 10 seconds.  I also tried setting it
to 86 in the device tree with similar success.

===

The above seem to cover all the cases I can think of.

Tested-by: Douglas Anderson <dianders@...omium.org>