[PATCH v6 0/2] mmc: core: hw_reset changes

[PATCH v6 0/2] mmc: core: hw_reset changes

[Johan Rudholm]

Make the mmc_hw_reset routine more generic, by putting the (e)MMC-
specific stuff in the new bus_ops->hw_reset in mmc.c. Add a
bus_ops->hw_reset for SD cards, allowing them to be restarted when
errors occur.

Always check if the reset was sucessful and propagate this to the
caller.

As I don't have an eMMC device myself, much less one with a reset line,
I'd be very happy if someone could help me test the code with an eMMC?

v6:
 - Always perform the mmc_send_status reset check, which allows us to
   have only one interface to the card reset functions
 - Because of this, add the bus_ops->hw_reset to sd.c instead of
   falling back to a power_cycle

v5:
 - Move the mmc_test-specific code to mmc_test.c
 - Fall back to a power_cycle if the bus_ops->hw_reset is missing
 - Because of this, skip the bus_ops->hw_reset in sd.c

v4:
 - Rebase onto next

v3:
 - Keep mmc_can_reset
 - Always set bus_mode = MMC_BUSMODE_PUSHPULL in mmc_set_initial_state()

v2:
 - Call the new bus_ops member hw_reset instead of power_reset
 - Create mmc_set_initial_state and call it from mmc_mmc_hw_reset
   instead of mmc_power_up
 - Keep "mmc_hw_reset" naming

Johan Rudholm (2):
  mmc: core: refactor the hw_reset routines
  mmc: sd: add hw_reset callback

 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 +++++++++++++++++++
 drivers/mmc/core/sd.c       |    7 ++++
 include/linux/mmc/core.h    |    1 -
 6 files changed, 71 insertions(+), 58 deletions(-)

-- 
1.7.2.5

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

[Johan Rudholm]

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);
-}
-
-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 *);
 };
 
 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)
+{
+	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

[PATCH v6 2/2] mmc: sd: add hw_reset callback

[Johan Rudholm]

Enable power cycle and re-initialization of SD cards via the hw_reset
bus_ops. Power cycling a buggy SD card sometimes helps it get back on
track.

Signed-off-by: Johan Rudholm <johanru@axis.com>
---
 drivers/mmc/core/sd.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 29fccdc..1228ef7 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -1197,6 +1197,12 @@ static int mmc_sd_power_restore(struct mmc_host *host)
 	return ret;
 }
 
+static int mmc_sd_hw_reset(struct mmc_host *host)
+{
+	mmc_power_cycle(host, host->card->ocr);
+	return 0;
+}
+
 static const struct mmc_bus_ops mmc_sd_ops = {
 	.remove = mmc_sd_remove,
 	.detect = mmc_sd_detect,
@@ -1207,6 +1213,7 @@ static const struct mmc_bus_ops mmc_sd_ops = {
 	.power_restore = mmc_sd_power_restore,
 	.alive = mmc_sd_alive,
 	.shutdown = mmc_sd_suspend,
+	.hw_reset = mmc_sd_hw_reset,
 };
 
 /*
-- 
1.7.2.5

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

[Ulf Hansson]

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

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

[Johan Rudholm]

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