Re: [PATCH v2] mmc: usdhi6rol0: Implement card_busy function

[Marten Lindahl <martenli@axis.com>]

On Mon, Aug 16, 2021 at 03:57:18PM +0200, Ulf Hansson wrote:
> On Mon, 16 Aug 2021 at 14:53, Mårten Lindahl <marten.lindahl@axis.com> wrote:
> >
> > When switching card voltage to UHS voltage the mmc framework tries to
> > check the card busy signal, meaning the card pulling DAT0 line low,
> > before the switch is made. Drivers that does not implement the card_busy
> > function will manage to do the switch anyway, but the framework will
> > print a warning about not being able to verify the voltage signal.
> >
> > Implement card_busy function.
> >
> > Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
> > ---
> >
> > v2:
> >  - Update commit message, since interface limitation for checking DAT
> >    lines is not valid for this fix.
> >  - Skip check of SCLKDIVEN bit, and skip check of DAT3 line since SD
> >    specification only points out checking DAT0 for busy signal.
> >  - Update comment about card_busy callback.
> >
> >  drivers/mmc/host/usdhi6rol0.c | 10 ++++++++++
> >  include/linux/mmc/host.h      |  2 +-
> 
> The change looks good to me, but I would be even happier if you could
> split this into two patches. Would you mind?
> 
> Kind regards
> Uffe

Ok, yes I can do that. I will send a separate patch for updating the
header file.

Kind regards
Mårten

> 
> >  2 files changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mmc/host/usdhi6rol0.c b/drivers/mmc/host/usdhi6rol0.c
> > index b9b79b1089a0..b5ab133e9add 100644
> > --- a/drivers/mmc/host/usdhi6rol0.c
> > +++ b/drivers/mmc/host/usdhi6rol0.c
> > @@ -1186,6 +1186,15 @@ static int usdhi6_sig_volt_switch(struct mmc_host *mmc, struct mmc_ios *ios)
> >         return ret;
> >  }
> >
> > +static int usdhi6_card_busy(struct mmc_host *mmc)
> > +{
> > +       struct usdhi6_host *host = mmc_priv(mmc);
> > +       u32 tmp = usdhi6_read(host, USDHI6_SD_INFO2);
> > +
> > +       /* Card is busy if it is pulling dat[0] low */
> > +       return !(tmp & USDHI6_SD_INFO2_SDDAT0);
> > +}
> > +
> >  static const struct mmc_host_ops usdhi6_ops = {
> >         .request        = usdhi6_request,
> >         .set_ios        = usdhi6_set_ios,
> > @@ -1193,6 +1202,7 @@ static const struct mmc_host_ops usdhi6_ops = {
> >         .get_ro         = usdhi6_get_ro,
> >         .enable_sdio_irq = usdhi6_enable_sdio_irq,
> >         .start_signal_voltage_switch = usdhi6_sig_volt_switch,
> > +       .card_busy = usdhi6_card_busy,
> >  };
> >
> >  /*                     State machine handlers                          */
> > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> > index 0abd47e9ef9b..ff1a251bb0bc 100644
> > --- a/include/linux/mmc/host.h
> > +++ b/include/linux/mmc/host.h
> > @@ -153,7 +153,7 @@ struct mmc_host_ops {
> >
> >         int     (*start_signal_voltage_switch)(struct mmc_host *host, struct mmc_ios *ios);
> >
> > -       /* Check if the card is pulling dat[0:3] low */
> > +       /* Check if the card is pulling dat[0] low */
> >         int     (*card_busy)(struct mmc_host *host);
> >
> >         /* The tuning command opcode value is different for SD and eMMC cards */
> > --
> > 2.20.1
> >