Re: [PATCH v6 1/2] mmc: core: refactor the hw_reset routines

Ulf Hansson
2015-01-12T12:55:51Z

On 9 January 2015 at 12:08, Johan Rudholm <johan.rudholm@axis.com> wrote:
> Move the (e)MMC specific hw_reset code from core.c into mmc.c Call the
> code from the new bus_ops member hw_reset. This also allows for adding
> a SD card specific reset procedure.
>
> Always check if the card is alive after a successful reset. This allows
> us to remove mmc_hw_reset_check(), leaving mmc_hw_reset() as the only
> card reset interface. This also informs any callers, for instance the
> block layer, if a reset was sucessful or not.
>
> Signed-off-by: Johan Rudholm <johanru@axis.com>
> ---
> drivers/mmc/card/mmc_test.c | 18 ++++-------
> drivers/mmc/core/core.c | 70 +++++++++++++++----------------------------
> drivers/mmc/core/core.h | 1 +
> drivers/mmc/core/mmc.c | 32 +++++++++++++++++++
> include/linux/mmc/core.h | 1 -
> 5 files changed, 64 insertions(+), 58 deletions(-)
>
> diff --git a/drivers/mmc/card/mmc_test.c b/drivers/mmc/card/mmc_test.c
> index 0a7430f..7dac469 100644
> --- a/drivers/mmc/card/mmc_test.c
> +++ b/drivers/mmc/card/mmc_test.c
> @@ -2342,20 +2342,16 @@ static int mmc_test_hw_reset(struct mmc_test_card *test)
> struct mmc_host *host = card->host;
> int err;
>
> - err = mmc_hw_reset_check(host);
> + if (!mmc_card_mmc(card) || !mmc_can_reset(card))
> + return RESULT_UNSUP_CARD;
> +
> + err = mmc_hw_reset(host);
> if (!err)
> return RESULT_OK;
> + else if (err == -EOPNOTSUPP)
> + return RESULT_UNSUP_HOST;
>
> - if (err == -ENOSYS)
> - return RESULT_FAIL;
> -
> - if (err != -EOPNOTSUPP)
> - return err;
> -
> - if (!mmc_can_reset(card))
> - return RESULT_UNSUP_CARD;
> -
> - return RESULT_UNSUP_HOST;
> + return RESULT_FAIL;
> }
>
> static const struct mmc_test_case mmc_test_cases[] = {
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index d3bfbdf..8598287 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2273,67 +2273,45 @@ static void mmc_hw_reset_for_init(struct mmc_host *host)
> mmc_host_clk_release(host);
> }
>
> -int mmc_can_reset(struct mmc_card *card)
> -{
> - u8 rst_n_function;
> -
> - if (!mmc_card_mmc(card))
> - return 0;
> - rst_n_function = card->ext_csd.rst_n_function;
> - if ((rst_n_function & EXT_CSD_RST_N_EN_MASK) != EXT_CSD_RST_N_ENABLED)
> - return 0;
> - return 1;
> -}
> -EXPORT_SYMBOL(mmc_can_reset);
> -
> -static int mmc_do_hw_reset(struct mmc_host *host, int check)
> +int mmc_hw_reset(struct mmc_host *host)
> {
> - struct mmc_card *card = host->card;
> -
> - if (!(host->caps & MMC_CAP_HW_RESET) || !host->ops->hw_reset)
> - return -EOPNOTSUPP;
> + int ret = 0;
> + int card_alive = 0;
> + u32 status;
>
> - if (!card)
> + if (!host->card)
> return -EINVAL;
>
> - if (!mmc_can_reset(card))
> - return -EOPNOTSUPP;
> -
> - mmc_host_clk_hold(host);
> - mmc_set_clock(host, host->f_init);
> + mmc_bus_get(host);
> + if (!host->bus_ops || host->bus_dead || !host->bus_ops->hw_reset) {
> + ret = -EOPNOTSUPP;
> + goto out;
> + }
>
> - host->ops->hw_reset(host);
> + ret = host->bus_ops->hw_reset(host);
> + if (ret)
> + goto out;
>
> /* If the reset has happened, then a status command will fail */
> - if (check) {
> - u32 status;
> + if (!mmc_send_status(host->card, &status))
> + card_alive = 1;
>
> - if (!mmc_send_status(card, &status)) {
> - mmc_host_clk_release(host);
> - return -ENOSYS;
> - }
> - }
> + pr_warn("%s: tried to reset card (%s)\n", mmc_hostname(host),
> + card_alive ? "failed" : "ok");
>
> /* Set initial state and call mmc_set_ios */
> mmc_set_initial_state(host);
> + ret = host->bus_ops->power_restore(host);
>
> - mmc_host_clk_release(host);
> -
> - return host->bus_ops->power_restore(host);

I would like you to move the mmc_send_status() and onwards code in
this function, into the mmc specific ->hw_reset() callback.

In that way, mmc/sd/sdio can separately decide if the
mmc_send_status() is needed and we also can remove two users (sd/mmc)
of the ->power_restore() callback.

> -}
> -
> -int mmc_hw_reset(struct mmc_host *host)
> -{
> - return mmc_do_hw_reset(host, 0);
> +out:
> + mmc_bus_put(host);
> + if (card_alive)
> + return -ENOSYS;
> + else
> + return ret;
> }
> EXPORT_SYMBOL(mmc_hw_reset);
>
> -int mmc_hw_reset_check(struct mmc_host *host)
> -{
> - return mmc_do_hw_reset(host, 1);
> -}
> -EXPORT_SYMBOL(mmc_hw_reset_check);
> -
> static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
> {
> host->f_init = freq;
> diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
> index b528c0e..4d1ee8a 100644
> --- a/drivers/mmc/core/core.h
> +++ b/drivers/mmc/core/core.h
> @@ -27,6 +27,7 @@ struct mmc_bus_ops {
> int (*power_restore)(struct mmc_host *);
> int (*alive)(struct mmc_host *);
> int (*shutdown)(struct mmc_host *);
> + int (*hw_reset)(struct mmc_host *);

->Please rename to reset()

> };
>
> void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops);
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 0b8ec87..f64a53e 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1795,6 +1795,37 @@ static int mmc_power_restore(struct mmc_host *host)
> return ret;
> }
>
> +int mmc_can_reset(struct mmc_card *card)
> +{
> + u8 rst_n_function;
> +
> + rst_n_function = card->ext_csd.rst_n_function;
> + if ((rst_n_function & EXT_CSD_RST_N_EN_MASK) != EXT_CSD_RST_N_ENABLED)
> + return 0;
> + return 1;
> +}
> +EXPORT_SYMBOL(mmc_can_reset);
> +
> +static int mmc_mmc_hw_reset(struct mmc_host *host)

Please rename to mmc_reset()

> +{
> + struct mmc_card *card = host->card;
> +
> + if (!(host->caps & MMC_CAP_HW_RESET) || !host->ops->hw_reset)
> + return -EOPNOTSUPP;
> +
> + if (!mmc_can_reset(card))
> + return -EOPNOTSUPP;
> +
> + mmc_host_clk_hold(host);
> + mmc_set_clock(host, host->f_init);
> +
> + host->ops->hw_reset(host);
> +
> + mmc_host_clk_release(host);
> +
> + return 0;
> +}
> +
> static const struct mmc_bus_ops mmc_ops = {
> .remove = mmc_remove,
> .detect = mmc_detect,
> @@ -1805,6 +1836,7 @@ static const struct mmc_bus_ops mmc_ops = {
> .power_restore = mmc_power_restore,
> .alive = mmc_alive,
> .shutdown = mmc_shutdown,
> + .hw_reset = mmc_mmc_hw_reset,
> };
>
> /*
> diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
> index cb2b040..160448f 100644
> --- a/include/linux/mmc/core.h
> +++ b/include/linux/mmc/core.h
> @@ -182,7 +182,6 @@ extern int mmc_set_blocklen(struct mmc_card *card, unsigned int blocklen);
> extern int mmc_set_blockcount(struct mmc_card *card, unsigned int blockcount,
> bool is_rel_write);
> extern int mmc_hw_reset(struct mmc_host *host);
> -extern int mmc_hw_reset_check(struct mmc_host *host);
> extern int mmc_can_reset(struct mmc_card *card);
>
> extern void mmc_set_data_timeout(struct mmc_data *, const struct mmc_card *);
> --
> 1.7.2.5
>

I am overall very happy with this approach. Nice work Johan!

Kind regards
Uffe