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

Johan Rudholm
2015-01-12T14:38:02Z

2015-01-12 13:55 GMT+01:00 Ulf Hansson <ulf.hansson@linaro.org>:
> 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.

Good idea, this makes the core.c code cleaner. I've decided to put the
removal of mmc_hw_reset_check() into a separate patch, to make it
easier to see what's happened.

>> -}
>> -
>> -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()

Ok.

>> };
>>
>> 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()

Ok.

>> +{
>> + 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!

Thank you, and thank you for the detailed review work!

//Johan