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Subject[PATCH 0/2] mmc: core: Fix Marvell WiFi reset by adding SDIO API to replug card
Date
As talked about in the thread at:

http://lkml.kernel.org/r/CAD=FV=X7P2F1k_zwHc0mbtfk55-rucTz_GoDH=PL6zWqKYcpuw@mail.gmail.com

...when the Marvell WiFi card tries to reset itself it kills
Bluetooth. It was observed that we could re-init the card properly by
unbinding / rebinding the host controller. It was also observed that
in the downstream Chrome OS codebase the solution used was
mmc_remove_host() / mmc_add_host(), which is similar to the solution
in this series.

So far I've only done testing of this series using the reset test
source that can be simulated via sysfs. Specifically I ran this test:

for i in $(seq 1000); do
echo "LOOP $i --------"
echo 1 > /sys/kernel/debug/mwifiex/mlan0/reset

while true; do
if ! ping -w15 -c1 "${GW}" >/dev/null 2>&1; then
fail=$(( fail + 1 ))
echo "Fail WiFi ${fail}"
if [[ ${fail} == 3 ]]; then
exit 1
fi
else
fail=0
break
fi
done

hciconfig hci0 down
sleep 1
if ! hciconfig hci0 up; then
echo "Fail BT"
exit 1
fi
done

I ran this several times and got several hundred iterations each
before a failure. When I saw failures:

* Once I saw a "Fail BT"; manually resetting the card again fixed it.
I didn't give it time to see if it would have detected this
automatically.
* Once I saw the ping fail because (for some reason) my device only
got an IPv6 address from my router and the IPv4 ping failed. I
changed my script to use 'ping6' to see if that would help.
* Once I saw the ping fail because the higher level network stack
("shill" in my case) seemed to crash. A few minutes later the
system recovered itself automatically. https://crbug.com/984593 if
you want more details.
* Sometimes while I was testing I saw "Fail WiFi 1" indicating a
transitory failure. Usually this was an association failure, but in
one case I saw the device do "Firmware wakeup failed" after I
triggered the reset. This caused the driver to trigger a re-reset
of itself which eventually recovered things. This was good because
it was an actual test of the normal reset flow (not the one
triggered via sysfs).


Douglas Anderson (2):
mmc: core: Add sdio_trigger_replug() API
mwifiex: Make use of the new sdio_trigger_replug() API to reset

drivers/mmc/core/core.c | 28 +++++++++++++++++++--
drivers/mmc/core/sdio_io.c | 20 +++++++++++++++
drivers/net/wireless/marvell/mwifiex/sdio.c | 14 +++--------
include/linux/mmc/host.h | 15 ++++++++++-
include/linux/mmc/sdio_func.h | 2 ++
5 files changed, 65 insertions(+), 14 deletions(-)

--
2.22.0.510.g264f2c817a-goog

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