mmc: revert deferred resume

Revert MMC_BLOCK_DEFERRED_RESUME feature from SD driver. The feature
was not implemented thread-safe. Fixing it would require a lot
of locking logic at limited value.

Deferred resume has no effect on eMMC, because eMMC will be used right
after resume. For SD card it only saves power between resume and first
SD card access, which is a limited usecase. It does not save power
on normal SD card idle.

Bug 833034

Change-Id: Ic6c9d751f463ef8135d0cf4c845462598fab774c
Reviewed-on: http://git-master/r/36451
Reviewed-by: David Schalig <dschalig@nvidia.com>
Tested-by: David Schalig <dschalig@nvidia.com>
Reviewed-by: Alex Courbot <acourbot@nvidia.com>
Reviewed-by: Sachin Nikam <snikam@nvidia.com>
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

4 files changed, 1 insertions, 94 deletions

diff --git a/drivers/mmc/card/Kconfig b/drivers/mmc/card/Kconfig
index 86948f90c3ff..3f2a912659af 100644
--- a/drivers/mmc/card/Kconfig
+++ b/drivers/mmc/card/Kconfig
@@ -32,15 +32,6 @@ config MMC_BLOCK_BOUNCE
 
 	  If unsure, say Y here.
 
-config MMC_BLOCK_DEFERRED_RESUME
-	bool "Deferr MMC layer resume until I/O is requested"
-	depends on MMC_BLOCK
-	default n
-	help
-	  Say Y here to enable deferred MMC resume until I/O
-	  is requested. This will reduce overall resume latency and
-	  save power when theres an SD card inserted but not being used.
-
 config SDIO_UART
 	tristate "SDIO UART/GPS class support"
 	help
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index e6f74718e06f..7c136c29a11a 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -575,21 +575,8 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
 	return 0;
 }
 
-static int
-mmc_blk_set_blksize(struct mmc_blk_data *md, struct mmc_card *card);
-
 static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 {
-#ifdef CONFIG_MMC_BLOCK_DEFERRED_RESUME
-	struct mmc_blk_data *md = mq->data;
-	struct mmc_card *card = md->queue.card;
-
-	if (mmc_bus_needs_resume(card->host)) {
-		mmc_resume_bus(card->host);
-		mmc_blk_set_blksize(md, card);
-	}
-#endif
-
 	if (req->cmd_flags & REQ_DISCARD) {
 		if (req->cmd_flags & REQ_SECURE)
 			return mmc_blk_issue_secdiscard_rq(mq, req);
@@ -712,7 +699,7 @@ mmc_blk_set_blksize(struct mmc_blk_data *md, struct mmc_card *card)
 
 	if (err) {
 		printk(KERN_ERR "%s: unable to set block size to %d: %d\n",
-                       md->disk->disk_name, cmd.arg, err);
+			md->disk->disk_name, cmd.arg, err);
 		return -EINVAL;
 	}
 
@@ -756,9 +743,6 @@ static int mmc_blk_probe(struct mmc_card *card)
 	mmc_set_drvdata(card, md);
 	mmc_fixup_device(card, blk_fixups);
 
-#ifdef CONFIG_MMC_BLOCK_DEFERRED_RESUME
-	mmc_set_bus_resume_policy(card->host, 1);
-#endif
 	add_disk(md->disk);
 	return 0;
 
@@ -783,9 +767,6 @@ static void mmc_blk_remove(struct mmc_card *card)
 		mmc_blk_put(md);
 	}
 	mmc_set_drvdata(card, NULL);
-#ifdef CONFIG_MMC_BLOCK_DEFERRED_RESUME
-	mmc_set_bus_resume_policy(card->host, 0);
-#endif
 }
 
 #ifdef CONFIG_PM
@@ -804,9 +785,7 @@ static int mmc_blk_resume(struct mmc_card *card)
 	struct mmc_blk_data *md = mmc_get_drvdata(card);
 
 	if (md) {
-#ifndef CONFIG_MMC_BLOCK_DEFERRED_RESUME
 		mmc_blk_set_blksize(md, card);
-#endif
 		mmc_queue_resume(&md->queue);
 	}
 	return 0;
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index c3225d68d9a5..c8384a8e6819 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1040,36 +1040,6 @@ static inline void mmc_bus_put(struct mmc_host *host)
 	spin_unlock_irqrestore(&host->lock, flags);
 }
 
-int mmc_resume_bus(struct mmc_host *host)
-{
-	unsigned long flags;
-
-	if (!mmc_bus_needs_resume(host))
-		return -EINVAL;
-
-	printk("%s: Starting deferred resume\n", mmc_hostname(host));
-	spin_lock_irqsave(&host->lock, flags);
-	host->bus_resume_flags &= ~MMC_BUSRESUME_NEEDS_RESUME;
-	host->rescan_disable = 0;
-	spin_unlock_irqrestore(&host->lock, flags);
-
-	mmc_bus_get(host);
-	if (host->bus_ops && !host->bus_dead) {
-		mmc_power_up(host);
-		BUG_ON(!host->bus_ops->resume);
-		host->bus_ops->resume(host);
-
-		if (host->bus_ops->detect)
-			host->bus_ops->detect(host);
-	}
-
-	mmc_bus_put(host);
-	printk("%s: Deferred resume completed\n", mmc_hostname(host));
-	return 0;
-}
-
-EXPORT_SYMBOL(mmc_resume_bus);
-
 /*
  * Assign a mmc bus handler to a host. Only one bus handler may control a
  * host at any given time.
@@ -1730,9 +1700,6 @@ int mmc_suspend_host(struct mmc_host *host)
 {
 	int err = 0;
 
-	if (mmc_bus_needs_resume(host))
-		return 0;
-
 	if (host->caps & MMC_CAP_DISABLE)
 		cancel_delayed_work(&host->disable);
 	cancel_delayed_work(&host->detect);
@@ -1775,12 +1742,6 @@ int mmc_resume_host(struct mmc_host *host)
 	int err = 0;
 
 	mmc_bus_get(host);
-	if (mmc_bus_manual_resume(host)) {
-		host->bus_resume_flags |= MMC_BUSRESUME_NEEDS_RESUME;
-		mmc_bus_put(host);
-		return 0;
-	}
-
 	if (host->bus_ops && !host->bus_dead) {
 		if (!(host->pm_flags & MMC_PM_KEEP_POWER)) {
 			mmc_power_up(host);
@@ -1818,10 +1779,6 @@ int mmc_pm_notify(struct notifier_block *notify_block,
 	case PM_SUSPEND_PREPARE:
 
 		spin_lock_irqsave(&host->lock, flags);
-		if (mmc_bus_needs_resume(host)) {
-			spin_unlock_irqrestore(&host->lock, flags);
-			break;
-		}
 		host->rescan_disable = 1;
 		spin_unlock_irqrestore(&host->lock, flags);
 		cancel_delayed_work_sync(&host->detect);
@@ -1845,10 +1802,6 @@ int mmc_pm_notify(struct notifier_block *notify_block,
 
 		spin_lock_irqsave(&host->lock, flags);
 		host->rescan_disable = 0;
-		if (mmc_bus_manual_resume(host)) {
-			spin_unlock_irqrestore(&host->lock, flags);
-			break;
-		}
 		spin_unlock_irqrestore(&host->lock, flags);
 		mmc_detect_change(host, 0);
 
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 62ffcb05fb78..7076851d9c2c 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -230,10 +230,6 @@ struct mmc_host {
 	const struct mmc_bus_ops *bus_ops;	/* current bus driver */
 	unsigned int		bus_refs;	/* reference counter */
 
-	unsigned int		bus_resume_flags;
-#define MMC_BUSRESUME_MANUAL_RESUME	(1 << 0)
-#define MMC_BUSRESUME_NEEDS_RESUME	(1 << 1)
-
 	unsigned int		tuning_status;
 #define MMC_SD_TUNING_COMPLETED	(1 << 0)
 #define MMC_SD_SAMPLING_CLOCK_SELECT_SET	(1 << 1)
@@ -287,18 +283,6 @@ static inline void *mmc_priv(struct mmc_host *host)
 #define mmc_dev(x)	((x)->parent)
 #define mmc_classdev(x)	(&(x)->class_dev)
 #define mmc_hostname(x)	(dev_name(&(x)->class_dev))
-#define mmc_bus_needs_resume(host) ((host)->bus_resume_flags & MMC_BUSRESUME_NEEDS_RESUME)
-#define mmc_bus_manual_resume(host) ((host)->bus_resume_flags & MMC_BUSRESUME_MANUAL_RESUME)
-
-static inline void mmc_set_bus_resume_policy(struct mmc_host *host, int manual)
-{
-	if (manual)
-		host->bus_resume_flags |= MMC_BUSRESUME_MANUAL_RESUME;
-	else
-		host->bus_resume_flags &= ~MMC_BUSRESUME_MANUAL_RESUME;
-}
-
-extern int mmc_resume_bus(struct mmc_host *host);
 
 extern int mmc_suspend_host(struct mmc_host *);
 extern int mmc_resume_host(struct mmc_host *);