Date:   Wed, 11 Sep 2019 14:26:04 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Kalle Valo <kvalo@...eaurora.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ganapathi Bhat <gbhat@...vell.com>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Andreas Fenkart <afenkart@...il.com>,
        Brian Norris <briannorris@...omium.org>,
        Amitkumar Karwar <amitkarwar@...il.com>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Nishant Sarmukadam <nishants@...vell.com>,
        netdev <netdev@...r.kernel.org>,
        Avri Altman <avri.altman@....com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Xinming Hu <huxinming820@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kate Stewart <kstewart@...uxfoundation.org>
Subject: Re: [PATCH v2 0/2] mmc: core: Fix Marvell WiFi reset by adding SDIO
 API to replug card

Hi,

On Thu, Jul 25, 2019 at 6:28 AM Ulf Hansson <ulf.hansson@...aro.org> wrote:
>
> On Mon, 22 Jul 2019 at 21:41, Douglas Anderson <dianders@...omium.org> wrote:
> >
> > 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).
> >
> > 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.

I had kinda forgotten about this series after we landed it locally in
Chrome OS, but I realized that it never got resolved upstream.  Any
chance your head has been sufficiently scratched and you're now happy
with $subject series?  ;-)

-Doug

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