mmc: Fix hangs related to insert/remove of cards

In the error handling of mmc_attach(sd|mmc|sdio) functions, the
bus can be detached. A detach triggered also a power_off, which
was the key reason to the issue.

If a power_off has been done, the framework must never send any
new commands/requests to the host driver, without first doing a
new power_up. This occured in the rescan sequence most likely
triggering ANY host driver to hang.

Moving power_off out of detach and instead handle power_off
separate when it is actually needed, solves the issue.

ST-Ericsson Linux next: -
ST-Ericsson ID: 339637
ST-Ericsson FOSS-OUT ID: Trivial

Change-Id: I9fefe95c4331b98b9f460b8309594ed32037cf2f
Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
Signed-off-by: Daniel Willerud <daniel.willerud@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/23841
Reviewed-by: Sebastian RASMUSSEN <sebastian.rasmussen@stericsson.com>
Reviewed-by: Joakim AXELSSON <joakim.axelsson@stericsson.com>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>

5 files changed, 22 insertions, 10 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 69cda159113..6aee8313018 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1091,8 +1091,7 @@ void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops)
 }
 
 /*
- * Remove the current bus handler from a host. Assumes that there are
- * no interesting cards left, so the bus is powered down.
+ * Remove the current bus handler from a host.
  */
 void mmc_detach_bus(struct mmc_host *host)
 {
@@ -1109,8 +1108,6 @@ void mmc_detach_bus(struct mmc_host *host)
 
 	spin_unlock_irqrestore(&host->lock, flags);
 
-	mmc_power_off(host);
-
 	mmc_bus_put(host);
 }
 
@@ -1549,8 +1546,15 @@ void mmc_rescan(struct work_struct *work)
 	 * still present
 	 */
 	if (host->bus_ops && host->bus_ops->detect && !host->bus_dead
-	    && !(host->caps & MMC_CAP_NONREMOVABLE))
-		host->bus_ops->detect(host);
+	    && !(host->caps & MMC_CAP_NONREMOVABLE)) {
+
+		if (host->bus_ops->detect(host)) {
+			/* power off if the card was not re-detected */
+			mmc_claim_host(host);
+			mmc_power_off(host);
+			mmc_release_host(host);
+		}
+	}
 
 	/*
 	 * Let mmc_bus_put() free the bus/bus_ops if we've found that
@@ -1618,6 +1622,7 @@ void mmc_stop_host(struct mmc_host *host)
 
 		mmc_claim_host(host);
 		mmc_detach_bus(host);
+		mmc_power_off(host);
 		mmc_release_host(host);
 		mmc_bus_put(host);
 		return;
@@ -1825,6 +1830,7 @@ int mmc_pm_notify(struct notifier_block *notify_block,
 			host->bus_ops->remove(host);
 
 		mmc_detach_bus(host);
+		mmc_power_off(host);
 		mmc_release_host(host);
 		host->pm_flags = 0;
 		break;
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index 20b1c0831ea..ac43eeabf79 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -19,7 +19,7 @@ struct mmc_bus_ops {
 	int (*awake)(struct mmc_host *);
 	int (*sleep)(struct mmc_host *);
 	void (*remove)(struct mmc_host *);
-	void (*detect)(struct mmc_host *);
+	int (*detect)(struct mmc_host *);
 	int (*suspend)(struct mmc_host *);
 	int (*resume)(struct mmc_host *);
 	int (*power_save)(struct mmc_host *);
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 14e95f39a7b..a78d57ebad4 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -701,7 +701,7 @@ static void mmc_remove(struct mmc_host *host)
 /*
  * Card detection callback from host.
  */
-static void mmc_detect(struct mmc_host *host)
+static int mmc_detect(struct mmc_host *host)
 {
 	int err;
 
@@ -724,6 +724,8 @@ static void mmc_detect(struct mmc_host *host)
 		mmc_detach_bus(host);
 		mmc_release_host(host);
 	}
+
+	return err;
 }
 
 /*
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 6dac89fe053..4752312cc3a 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -661,7 +661,7 @@ static void mmc_sd_remove(struct mmc_host *host)
 /*
  * Card detection callback from host.
  */
-static void mmc_sd_detect(struct mmc_host *host)
+static int mmc_sd_detect(struct mmc_host *host)
 {
 	int err;
 
@@ -684,6 +684,8 @@ static void mmc_sd_detect(struct mmc_host *host)
 		mmc_detach_bus(host);
 		mmc_release_host(host);
 	}
+
+	return err;
 }
 
 /*
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index db0f0b44d68..8cdbbb4fc37 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -548,7 +548,7 @@ static void mmc_sdio_remove(struct mmc_host *host)
 /*
  * Card detection callback from host.
  */
-static void mmc_sdio_detect(struct mmc_host *host)
+static int mmc_sdio_detect(struct mmc_host *host)
 {
 	int err;
 
@@ -593,6 +593,8 @@ out:
 		mmc_detach_bus(host);
 		mmc_release_host(host);
 	}
+
+	return err;
 }
 
 /*