[linux-yocto] [PATCH 3/4] mmc: core: Add a facility to "pause" re-tuning

[California Sullivan]

From: Adrian Hunter <adrian.hunter at intel.com>

commit 7ff2760999a86e4d2b1af93dcf0f0d336c309571 upstream.

Re-tuning is not possible when switched to the RPMB
partition.  However re-tuning should not be needed
if re-tuning is done immediately before switching,
a small set of operations is done, and then we
immediately switch back to the main partition.

To ensure that re-tuning can't be done for a short
while, add a facility to "pause" re-tuning.

The existing facility to hold / release re-tuning
is used but it also flags re-tuning as needed to cause
re-tuning before the next command (which will be the
switch to RPMB).

We also need to "unpause" in the recovery path, which
is catered for by adding it to mmc_retune_disable().

Signed-off-by: Adrian Hunter <adrian.hunter at intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
Signed-off-by: California Sullivan <california.l.sullivan at intel.com>
---
 drivers/mmc/core/host.c  | 24 ++++++++++++++++++++++++
 include/linux/mmc/host.h |  4 ++++
 2 files changed, 28 insertions(+)

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index da950c4..e11a66d 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -69,8 +69,32 @@ void mmc_retune_enable(struct mmc_host *host)
 			  jiffies + host->retune_period * HZ);
 }
 
+/*
+ * Pause re-tuning for a small set of operations.  The pause begins after the
+ * next command and after first doing re-tuning.
+ */
+void mmc_retune_pause(struct mmc_host *host)
+{
+	if (!host->retune_paused) {
+		host->retune_paused = 1;
+		mmc_retune_needed(host);
+		mmc_retune_hold(host);
+	}
+}
+EXPORT_SYMBOL(mmc_retune_pause);
+
+void mmc_retune_unpause(struct mmc_host *host)
+{
+	if (host->retune_paused) {
+		host->retune_paused = 0;
+		mmc_retune_release(host);
+	}
+}
+EXPORT_SYMBOL(mmc_retune_unpause);
+
 void mmc_retune_disable(struct mmc_host *host)
 {
+	mmc_retune_unpause(host);
 	host->can_retune = 0;
 	del_timer_sync(&host->retune_timer);
 	host->retune_now = 0;
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 8673ffe..fb8e351 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -316,6 +316,7 @@ struct mmc_host {
 	unsigned int		can_retune:1;	/* re-tuning can be used */
 	unsigned int		doing_retune:1;	/* re-tuning in progress */
 	unsigned int		retune_now:1;	/* do re-tuning at next req */
+	unsigned int		retune_paused:1; /* re-tuning is temporarily disabled */
 
 	int			rescan_disable;	/* disable card detection */
 	int			rescan_entered;	/* used with nonremovable devices */
@@ -515,4 +516,7 @@ static inline void mmc_retune_recheck(struct mmc_host *host)
 		host->retune_now = 1;
 }
 
+void mmc_retune_pause(struct mmc_host *host);
+void mmc_retune_unpause(struct mmc_host *host);
+
 #endif /* LINUX_MMC_HOST_H */
-- 
2.5.5