[Linux-stm32] [PATCH v2 10/12] mmc: mmci: mmci_card_busy() from state machine

[Linus Walleij]

On Mon, Apr 17, 2023 at 4:49 PM Ulf Hansson <ulf.hansson at linaro.org> wrote:
> On Sun, 9 Apr 2023 at 00:00, Linus Walleij <linus.walleij at linaro.org> wrote:
> >
> > If we have a .busy_complete() callback, then check if
> > the state machine triggered from the busy detect interrupts
> > is busy: then we are certainly busy.
> >
> > Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
> > ---
> > ChangeLog v1->v2:
> > - Do this in a safer way that falls back to reading busy
> >   status from the hardware if the state machine is NOT
> >   busy.
> > ---
> >  drivers/mmc/host/mmci.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> > index 9a7f441ec9d6..180a7b719347 100644
> > --- a/drivers/mmc/host/mmci.c
> > +++ b/drivers/mmc/host/mmci.c
> > @@ -339,6 +339,12 @@ static int mmci_card_busy(struct mmc_host *mmc)
> >         unsigned long flags;
> >         int busy = 0;
> >
> > +       /* If we are waiting for IRQs we are certainly busy */
> > +       if (host->ops->busy_complete &&
> > +           host->busy_state != MMCI_BUSY_IDLE &&
> > +           host->busy_state != MMCI_BUSY_DONE)
> > +               return 1;
>
> This looks fishy to me.
>
> If this is needed, that means that the mmc core is calling the
> ->card_busy() ops in the middle of a request that has not been
> completed yet. This shouldn't happen - unless I am misunderstanding
> some part of the internal new state machine.

You're probably right about that, I have no idea when the core can
and cannot call ->card_busy, I just assumed it could be called at
any time (even while waiting for busy interrupts). If you say it won't
get called then this patch isn't needed.

Yours,
Linus Walleij