Re: [PATCH v2 0/2] mmc: core: Fix Marvell WiFi reset by adding SDIO API to replug card

From: Ulf Hansson
Date: Thu Jul 25 2019 - 14:06:34 EST


On Mon, 22 Jul 2019 at 21:41, Douglas Anderson <dianders@xxxxxxxxxxxx> wrote:
>
> As talked about in the thread at:
>
> http://lkml.kernel.org/r/CAD=FV=X7P2F1k_zwHc0mbtfk55-rucTz_GoDH=PL6zWqKYcpuw@xxxxxxxxxxxxxx
>
> ...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).
>
> Changes in v2:
> - s/routnine/routine (Brian Norris, Matthias Kaehlcke).
> - s/contining/containing (Matthias Kaehlcke).
> - Add Matthias Reviewed-by tag.
> - Removed clear_bit() calls and old comment (Brian Norris).
> - Explicit CC of Andreas Fenkart.
> - Explicit CC of Brian Norris.
> - Add "Fixes" pointing at the commit Brian talked about.
> - Add Brian's Reviewed-by tag.
>
> 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 | 16 +-----------
> include/linux/mmc/host.h | 15 ++++++++++-
> include/linux/mmc/sdio_func.h | 2 ++
> 5 files changed, 63 insertions(+), 18 deletions(-)
>

Doug, thanks for sending this!

As you know, I have been working on additional changes for SDIO
suspend/resume (still WIP and not ready for sharing) and this series
is related.

The thing is, that even during system suspend/resume, synchronizations
are needed between the different layers (mmc host, mmc core and
sdio-funcs), which is common to the problem you want to solve.

That said, I need to scratch my head a bit more before I can provide
you some feedback on $subject series. Moreover, it's vacation period
at my side so things are moving a bit slower. Please be patient.

Kind regards
Uffe