[PATCH v3 0/3] mmc: Fixup HW reset for SDIO cards

[PATCH v3 0/3] mmc: Fixup HW reset for SDIO cards

[Ulf Hansson]

Changes in v3:
	- Added tags.
	- Drop unnecessary initialization of variable.
	- Rename adapter->is_adapter_up to adapter->is_up in the mwifiex driver.

Changes in v2:
	- Add adaptations to the mwifiex driver.
	- Keep existing synchronous reset behaviour if the SDIO card has a
	single func driver.

The cover-letter from v2:

It has turned out that it's not a good idea to try to power cycle and to
re-initialize the SDIO card, as currently done through mmc_hw_reset(). This
because there may be multiple SDIO funcs attached to the same SDIO card and
some of the others that didn't execute the call to mmc_hw_reset(), may then
simply experience an undefined behaviour.

The following patches in this series attempts to address this problem, by
reworking the mmc_hw_reset() behaviour for SDIO and by adopting the Marvel
mwifiex driver to these changes.

Note that, I don't have the HW at hand so the the code has only compile tested.
Test on HW is greatly appreciated!


Ulf Hansson (3):
  mwifiex: Re-work support for SDIO HW reset
  mmc: core: Drop check for mmc_card_is_removable() in mmc_rescan()
  mmc: core: Re-work HW reset for SDIO cards

 drivers/mmc/core/core.c                     | 12 +++-----
 drivers/mmc/core/core.h                     |  2 ++
 drivers/mmc/core/sdio.c                     | 28 ++++++++++++++++-
 drivers/mmc/core/sdio_bus.c                 |  9 +++++-
 drivers/net/wireless/marvell/mwifiex/main.c |  5 +++-
 drivers/net/wireless/marvell/mwifiex/main.h |  1 +
 drivers/net/wireless/marvell/mwifiex/sdio.c | 33 ++++++++++++++-------
 include/linux/mmc/card.h                    |  1 +
 8 files changed, 69 insertions(+), 22 deletions(-)

-- 
2.17.1

[PATCH v3 1/3] mwifiex: Re-work support for SDIO HW reset

[Ulf Hansson]

The SDIO HW reset procedure in mwifiex_sdio_card_reset_work() is broken,
when the SDIO card is shared with another SDIO func driver. This is the
case when the Bluetooth btmrvl driver is being used in combination with
mwifiex. More precisely, when mwifiex_sdio_card_reset_work() runs to resets
the SDIO card, the btmrvl driver doesn't get notified about it. Beyond that
point, the btmrvl driver will fail to communicate with the SDIO card.

This is a generic problem for SDIO func drivers sharing an SDIO card, which
are about to be addressed in subsequent changes to the mmc core and the
mmc_hw_reset() interface. In principle, these changes means the
mmc_hw_reset() interface starts to return 1 if the are multiple drivers for
the SDIO card, as to indicate to the caller that the reset needed to be
scheduled asynchronously through a hotplug mechanism of the SDIO card.

Let's prepare the mwifiex driver to support the upcoming new behaviour of
mmc_hw_reset(), which means extending the mwifiex_sdio_card_reset_work() to
support the asynchronous SDIO HW reset path. This also means, we need to
allow the ->remove() callback to run, without waiting for the FW to be
loaded. Additionally, during system suspend, mwifiex_sdio_suspend() may be
called when a reset has been scheduled, but waiting to be executed. In this
scenario let's simply return -EBUSY to abort the suspend process, as to
allow the reset to be completed first.

Reviewed-by: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Tested-by: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Signed-off-by: Ulf Hansson <ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 drivers/net/wireless/marvell/mwifiex/main.c |  5 +++-
 drivers/net/wireless/marvell/mwifiex/main.h |  1 +
 drivers/net/wireless/marvell/mwifiex/sdio.c | 33 ++++++++++++++-------
 3 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/main.c b/drivers/net/wireless/marvell/mwifiex/main.c
index a9657ae6d782..d14e55e3c9da 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.c
+++ b/drivers/net/wireless/marvell/mwifiex/main.c
@@ -631,6 +631,7 @@ static int _mwifiex_fw_dpc(const struct firmware *firmware, void *context)
 
 	mwifiex_drv_get_driver_version(adapter, fmt, sizeof(fmt) - 1);
 	mwifiex_dbg(adapter, MSG, "driver_version = %s\n", fmt);
+	adapter->is_up = true;
 	goto done;
 
 err_add_intf:
@@ -1469,6 +1470,7 @@ int mwifiex_shutdown_sw(struct mwifiex_adapter *adapter)
 	mwifiex_deauthenticate(priv, NULL);
 
 	mwifiex_uninit_sw(adapter);
+	adapter->is_up = false;
 
 	if (adapter->if_ops.down_dev)
 		adapter->if_ops.down_dev(adapter);
@@ -1730,7 +1732,8 @@ int mwifiex_remove_card(struct mwifiex_adapter *adapter)
 	if (!adapter)
 		return 0;
 
-	mwifiex_uninit_sw(adapter);
+	if (adapter->is_up)
+		mwifiex_uninit_sw(adapter);
 
 	if (adapter->irq_wakeup >= 0)
 		device_init_wakeup(adapter->dev, false);
diff --git a/drivers/net/wireless/marvell/mwifiex/main.h b/drivers/net/wireless/marvell/mwifiex/main.h
index 095837fba300..547ff3c578ee 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.h
+++ b/drivers/net/wireless/marvell/mwifiex/main.h
@@ -1017,6 +1017,7 @@ struct mwifiex_adapter {
 
 	/* For synchronizing FW initialization with device lifecycle. */
 	struct completion *fw_done;
+	bool is_up;
 
 	bool ext_scan;
 	u8 fw_api_ver;
diff --git a/drivers/net/wireless/marvell/mwifiex/sdio.c b/drivers/net/wireless/marvell/mwifiex/sdio.c
index 24c041dad9f6..fec38b6e86ff 100644
--- a/drivers/net/wireless/marvell/mwifiex/sdio.c
+++ b/drivers/net/wireless/marvell/mwifiex/sdio.c
@@ -444,6 +444,9 @@ static int mwifiex_sdio_suspend(struct device *dev)
 		return 0;
 	}
 
+	if (!adapter->is_up)
+		return -EBUSY;
+
 	mwifiex_enable_wake(adapter);
 
 	/* Enable the Host Sleep */
@@ -2220,22 +2223,30 @@ static void mwifiex_sdio_card_reset_work(struct mwifiex_adapter *adapter)
 	struct sdio_func *func = card->func;
 	int ret;
 
+	/* Prepare the adapter for the reset. */
 	mwifiex_shutdown_sw(adapter);
+	clear_bit(MWIFIEX_IFACE_WORK_DEVICE_DUMP, &card->work_flags);
+	clear_bit(MWIFIEX_IFACE_WORK_CARD_RESET, &card->work_flags);
 
-	/* power cycle the adapter */
+	/* Run a HW reset of the SDIO interface. */
 	sdio_claim_host(func);
-	mmc_hw_reset(func->card->host);
+	ret = mmc_hw_reset(func->card->host);
 	sdio_release_host(func);
 
-	/* Previous save_adapter won't be valid after this. We will cancel
-	 * pending work requests.
-	 */
-	clear_bit(MWIFIEX_IFACE_WORK_DEVICE_DUMP, &card->work_flags);
-	clear_bit(MWIFIEX_IFACE_WORK_CARD_RESET, &card->work_flags);

Re: [PATCH v3 1/3] mwifiex: Re-work support for SDIO HW reset

[Kalle Valo]

Ulf Hansson <ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> writes:

> The SDIO HW reset procedure in mwifiex_sdio_card_reset_work() is broken,
> when the SDIO card is shared with another SDIO func driver. This is the
> case when the Bluetooth btmrvl driver is being used in combination with
> mwifiex. More precisely, when mwifiex_sdio_card_reset_work() runs to resets
> the SDIO card, the btmrvl driver doesn't get notified about it. Beyond that
> point, the btmrvl driver will fail to communicate with the SDIO card.
>
> This is a generic problem for SDIO func drivers sharing an SDIO card, which
> are about to be addressed in subsequent changes to the mmc core and the
> mmc_hw_reset() interface. In principle, these changes means the
> mmc_hw_reset() interface starts to return 1 if the are multiple drivers for
> the SDIO card, as to indicate to the caller that the reset needed to be
> scheduled asynchronously through a hotplug mechanism of the SDIO card.
>
> Let's prepare the mwifiex driver to support the upcoming new behaviour of
> mmc_hw_reset(), which means extending the mwifiex_sdio_card_reset_work() to
> support the asynchronous SDIO HW reset path. This also means, we need to
> allow the ->remove() callback to run, without waiting for the FW to be
> loaded. Additionally, during system suspend, mwifiex_sdio_suspend() may be
> called when a reset has been scheduled, but waiting to be executed. In this
> scenario let's simply return -EBUSY to abort the suspend process, as to
> allow the reset to be completed first.
>
> Reviewed-by: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> Tested-by: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> Signed-off-by: Ulf Hansson <ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

Look good to me. Ulf, I assume you are going to take this so here's my
ack:

Acked-by: Kalle Valo <kvalo-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>

But let me know if I should take it instead, whatever works the best for
you.

-- 
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH v3 1/3] mwifiex: Re-work support for SDIO HW reset

[Ulf Hansson]

On Thu, 14 Nov 2019 at 16:13, Kalle Valo <kvalo-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> wrote:
>
> Ulf Hansson <ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> writes:
>
> > The SDIO HW reset procedure in mwifiex_sdio_card_reset_work() is broken,
> > when the SDIO card is shared with another SDIO func driver. This is the
> > case when the Bluetooth btmrvl driver is being used in combination with
> > mwifiex. More precisely, when mwifiex_sdio_card_reset_work() runs to resets
> > the SDIO card, the btmrvl driver doesn't get notified about it. Beyond that
> > point, the btmrvl driver will fail to communicate with the SDIO card.
> >
> > This is a generic problem for SDIO func drivers sharing an SDIO card, which
> > are about to be addressed in subsequent changes to the mmc core and the
> > mmc_hw_reset() interface. In principle, these changes means the
> > mmc_hw_reset() interface starts to return 1 if the are multiple drivers for
> > the SDIO card, as to indicate to the caller that the reset needed to be
> > scheduled asynchronously through a hotplug mechanism of the SDIO card.
> >
> > Let's prepare the mwifiex driver to support the upcoming new behaviour of
> > mmc_hw_reset(), which means extending the mwifiex_sdio_card_reset_work() to
> > support the asynchronous SDIO HW reset path. This also means, we need to
> > allow the ->remove() callback to run, without waiting for the FW to be
> > loaded. Additionally, during system suspend, mwifiex_sdio_suspend() may be
> > called when a reset has been scheduled, but waiting to be executed. In this
> > scenario let's simply return -EBUSY to abort the suspend process, as to
> > allow the reset to be completed first.
> >
> > Reviewed-by: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> > Tested-by: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> > Signed-off-by: Ulf Hansson <ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>
> Look good to me. Ulf, I assume you are going to take this so here's my
> ack:
>
> Acked-by: Kalle Valo <kvalo-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>

Thanks, I have queued it via my tree this time.

Kind regards
Uffe

[PATCH v3 2/3] mmc: core: Drop check for mmc_card_is_removable() in mmc_rescan()

[Ulf Hansson]

Upfront in mmc_rescan() we use the host->rescan_entered flag, to allow
scanning only once for non-removable cards. Therefore, it's also not
possible that we can have a corresponding card bus attached (host->bus_ops
is NULL), when we are scanning non-removable cards.

For this reason, let' drop the check for mmc_card_is_removable() as it's
redundant.

Reviewed-by: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Tested-by: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Signed-off-by: Ulf Hansson <ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 drivers/mmc/core/core.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 221127324709..6f8342702c73 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2297,11 +2297,8 @@ void mmc_rescan(struct work_struct *work)
 
 	mmc_bus_get(host);
 
-	/*
-	 * if there is a _removable_ card registered, check whether it is
-	 * still present
-	 */
-	if (host->bus_ops && !host->bus_dead && mmc_card_is_removable(host))
+	/* Verify a registered card to be functional, else remove it. */
+	if (host->bus_ops && !host->bus_dead)
 		host->bus_ops->detect(host);
 
 	host->detect_change = 0;
-- 
2.17.1

[PATCH v3 3/3] mmc: core: Re-work HW reset for SDIO cards

[Ulf Hansson]

It have turned out that it's not a good idea to unconditionally do a power
cycle and then to re-initialize the SDIO card, as currently done through
mmc_hw_reset() -> mmc_sdio_hw_reset(). This because there may be multiple
SDIO func drivers probed, who also shares the same SDIO card.

To address these scenarios, one may be tempted to use a notification
mechanism, as to allow the core to inform each of the probed func drivers,
about an ongoing HW reset. However, supporting such an operation from the
func driver point of view, may not be entirely trivial.

Therefore, let's use a more simplistic approach to solve the problem, by
instead forcing the card to be removed and re-detected, via scheduling a
rescan-work. In this way, we can rely on existing infrastructure, as the
func driver's ->remove() and ->probe() callbacks, becomes invoked to deal
with the cleanup and the re-initialization.

This solution may be considered as rather heavy, especially if a func
driver doesn't share its card with other func drivers. To address this,
let's keep the current immediate HW reset option as well, but run it only
when there is one func driver probed for the card.

Finally, to allow the caller of mmc_hw_reset(), to understand if the reset
is being asynchronously managed from a scheduled work, it returns 1
(propagated from mmc_sdio_hw_reset()). If the HW reset is executed
successfully and synchronously it returns 0, which maintains the existing
behaviour.

Reviewed-by: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Tested-by: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Signed-off-by: Ulf Hansson <ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 drivers/mmc/core/core.c     |  5 ++---
 drivers/mmc/core/core.h     |  2 ++
 drivers/mmc/core/sdio.c     | 28 +++++++++++++++++++++++++++-
 drivers/mmc/core/sdio_bus.c |  9 ++++++++-
 include/linux/mmc/card.h    |  1 +
 5 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 6f8342702c73..abf8f5eb0a1c 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1469,8 +1469,7 @@ void mmc_detach_bus(struct mmc_host *host)
 	mmc_bus_put(host);
 }
 
-static void _mmc_detect_change(struct mmc_host *host, unsigned long delay,
-				bool cd_irq)
+void _mmc_detect_change(struct mmc_host *host, unsigned long delay, bool cd_irq)
 {
 	/*
 	 * If the device is configured as wakeup, we prevent a new sleep for
@@ -2129,7 +2128,7 @@ int mmc_hw_reset(struct mmc_host *host)
 	ret = host->bus_ops->hw_reset(host);
 	mmc_bus_put(host);
 
-	if (ret)
+	if (ret < 0)
 		pr_warn("%s: tried to HW reset card, got error %d\n",
 			mmc_hostname(host), ret);
 
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index 328c78dbee66..575ac0257af2 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -70,6 +70,8 @@ void mmc_rescan(struct work_struct *work);
 void mmc_start_host(struct mmc_host *host);
 void mmc_stop_host(struct mmc_host *host);
 
+void _mmc_detect_change(struct mmc_host *host, unsigned long delay,
+			bool cd_irq);
 int _mmc_detect_card_removed(struct mmc_host *host);
 int mmc_detect_card_removed(struct mmc_host *host);
 
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 26cabd53ddc5..ebb387aa5158 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -1048,9 +1048,35 @@ static int mmc_sdio_runtime_resume(struct mmc_host *host)
 	return ret;
 }
 
+/*
+ * SDIO HW reset
+ *
+ * Returns 0 if the HW reset was executed synchronously, returns 1 if the HW
+ * reset was asynchronously scheduled, else a negative error code.
+ */
 static int mmc_sdio_hw_reset(struct mmc_host *host)
 {
-	mmc_power_cycle(host, host->card->ocr);
+	struct mmc_card *card = host->card;
+
+	/*
+	 * In case the card is shared among multiple func drivers, reset the
+	 * card through a rescan work. In this way it will be removed and
+	 * re-detected, thus all func drivers becomes informed about it.
+	 */
+	if (atomic_read(&card->sdio_funcs_probed) > 1) {
+		if (mmc_card_removed(card))
+			return 1;
+		host->rescan_entered = 0;
+		mmc_card_set_removed(card);
+		_mmc_detect_change(host, 0, false);
+		return 1;
+	}
+
+	/*
+	 * A single func driver has been probed, then let's skip the heavy
+	 * hotplug dance above and execute the reset immediately.
+	 */
+	mmc_power_cycle(host, card->ocr);
 	return mmc_sdio_reinit_card(host);
 }
 
diff --git a/drivers/mmc/core/sdio_bus.c b/drivers/mmc/core/sdio_bus.c
index 2963e6542958..3cc928282af7 100644
--- a/drivers/mmc/core/sdio_bus.c
+++ b/drivers/mmc/core/sdio_bus.c
@@ -138,6 +138,8 @@ static int sdio_bus_probe(struct device *dev)
 	if (ret)
 		return ret;
 
+	atomic_inc(&func->card->sdio_funcs_probed);
+
 	/* Unbound SDIO functions are always suspended.
 	 * During probe, the function is set active and the usage count
 	 * is incremented.  If the driver supports runtime PM,
@@ -153,7 +155,10 @@ static int sdio_bus_probe(struct device *dev)
 	/* Set the default block size so the driver is sure it's something
 	 * sensible. */
 	sdio_claim_host(func);
-	ret = sdio_set_block_size(func, 0);
+	if (mmc_card_removed(func->card))
+		ret = -ENOMEDIUM;
+	else
+		ret = sdio_set_block_size(func, 0);
 	sdio_release_host(func);
 	if (ret)
 		goto disable_runtimepm;
@@ -165,6 +170,7 @@ static int sdio_bus_probe(struct device *dev)
 	return 0;
 
 disable_runtimepm:
+	atomic_dec(&func->card->sdio_funcs_probed);
 	if (func->card->host->caps & MMC_CAP_POWER_OFF_CARD)
 		pm_runtime_put_noidle(dev);
 	dev_pm_domain_detach(dev, false);
@@ -181,6 +187,7 @@ static int sdio_bus_remove(struct device *dev)
 		pm_runtime_get_sync(dev);
 
 	drv->remove(func);
+	atomic_dec(&func->card->sdio_funcs_probed);
 
 	if (func->irq_handler) {
 		pr_warn("WARNING: driver %s did not remove its interrupt handler!\n",
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 9b6336ad3266..e459b38ef33c 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -291,6 +291,7 @@ struct mmc_card {
 	struct sd_switch_caps	sw_caps;	/* switch (CMD6) caps */
 
 	unsigned int		sdio_funcs;	/* number of SDIO functions */
+	atomic_t		sdio_funcs_probed; /* number of probed SDIO funcs */
 	struct sdio_cccr	cccr;		/* common card info */
 	struct sdio_cis		cis;		/* common tuple info */
 	struct sdio_func	*sdio_func[SDIO_MAX_FUNCS]; /* SDIO functions (devices) */
-- 
2.17.1