Re: [PATCH v2 0/3] mmc: Fixup HW reset for SDIO cards

[Ulf Hansson <ulf.hansson@linaro.org>]

On Tue, 12 Nov 2019 at 01:51, Doug Anderson <dianders@chromium.org> wrote:
>
> Hi,
>
> On Sat, Nov 9, 2019 at 2:31 AM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> >
> > Changes in v2:
> >         - Add adaptations to the mwifiex driver.
> >         - Keep existing syncronous reset behaviour if the SDIO card has a single
> >         func driver.
> >
> > It has turned out that it's not a good idea to try to power cycle and to
> > re-initialize the SDIO card, as currently done through mmc_hw_reset(). This
> > because there may be multiple SDIO funcs attached to the same SDIO card and
> > some of the others that didn't execute the call to mmc_hw_reset(), may then
> > simply experience an undefined behaviour.
> >
> > The following patches in this series attempts to address this problem, by
> > reworking the mmc_hw_reset() behaviour for SDIO and by adopting the Marvel
> > mwifiex driver to these changes.
> >
> > Note that, I don't have the HW at hand so the the code has only compile tested.
> > Test on HW is greatly appreciated!
> >
> > Ulf Hansson (3):
> >   mwifiex: Re-work support for SDIO HW reset
> >   mmc: core: Drop check for mmc_card_is_removable() in mmc_rescan()
> >   mmc: core: Re-work HW reset for SDIO cards
> >
> >  drivers/mmc/core/core.c                     | 12 +++-----
> >  drivers/mmc/core/core.h                     |  2 ++
> >  drivers/mmc/core/sdio.c                     | 28 ++++++++++++++++-
> >  drivers/mmc/core/sdio_bus.c                 |  9 +++++-
> >  drivers/net/wireless/marvell/mwifiex/main.c |  6 +++-
> >  drivers/net/wireless/marvell/mwifiex/main.h |  1 +
> >  drivers/net/wireless/marvell/mwifiex/sdio.c | 33 ++++++++++++++-------
> >  include/linux/mmc/card.h                    |  1 +
> >  8 files changed, 70 insertions(+), 22 deletions(-)
>
> I put this on rk3288-veyron-jerry atop v5.4-rc7 and I could run my
> test case for a while, AKA I got over 50 cycles of:
>
> ---
>
> for i in $(seq 1000); do
>   echo "LOOP $i --------"
>   echo 1 > /sys/kernel/debug/mwifiex/mlan0/reset
>
>   while true; do
>     if ! ping6 -w15 -c1 "${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
>
> ---
>
> NOTE: with no patches I couldn't even get my test case to pass w/out
> the BT bits and I swear that used to work before.  ...but I didn't
> debug since the end result (with full card hotplug) is happy-working
> for me.  I'll still use it as further argument that (IMO) full unplug
> / plug of the card is better it uses more standard code paths and is
> less likely to break.  ;-)
>
> Tested-by: Douglas Anderson <dianders@chromium.org>

Thanks, I add this to the series and make a re-spin.

What do you think about tagging the patches for stable?

I guess there is a risk that we may "break" the other two users of
mmc_hw_reset(). But, as I said, in that case those needs to be fixed
anyways.

Kind regards
Uffe