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

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

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

>  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
>