From cfc51f6f0f342e1b30c00a170f2ff70d7f9bf658 Mon Sep 17 00:00:00 2001
From: San Mehat <san@google.com>
Date: Thu, 30 Jul 2009 08:21:19 -0700
Subject: [PATCH] mmc: mmcblk: Add support for deferred SD bus resume

Signed-off-by: San Mehat <san@google.com>

mmc: card: Add MMC_BLOCK_DEFERRED_RESUME option to Kconfig

Signed-off-by: San Mehat <san@google.com>
---
 drivers/mmc/card/Kconfig |  9 +++++++++
 drivers/mmc/card/block.c | 23 ++++++++++++++++++++++-
 drivers/mmc/core/core.c  |  6 ++++++
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/card/Kconfig b/drivers/mmc/card/Kconfig
index 3f2a912659af..86948f90c3ff 100644
--- a/drivers/mmc/card/Kconfig
+++ b/drivers/mmc/card/Kconfig
@@ -32,6 +32,15 @@ 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 d545f79f6000..a21861b90156 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -544,8 +544,21 @@ 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);
@@ -667,7 +680,7 @@ 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;
 	}
 
@@ -702,6 +715,9 @@ static int mmc_blk_probe(struct mmc_card *card)
 		cap_str, md->read_only ? "(ro)" : "");
 
 	mmc_set_drvdata(card, md);
+#ifdef CONFIG_MMC_BLOCK_DEFERRED_RESUME
+	mmc_set_bus_resume_policy(card->host, 1);
+#endif
 	add_disk(md->disk);
 	return 0;
 
@@ -726,6 +742,9 @@ 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
@@ -744,7 +763,9 @@ 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 70a037099a1a..bfde706b7236 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1449,6 +1449,12 @@ void mmc_rescan(struct work_struct *work)
 	if ((host->bus_ops != NULL) && host->bus_ops->detect && !host->bus_dead)
 		host->bus_ops->detect(host);
 
+	/* If the card was removed the bus will be marked
+	 * as dead - extend the wakelock so userspace
+	 * can respond */
+	if (host->bus_dead)
+		extend_wakelock = 1;
+
 	mmc_bus_put(host);
 
 
-- 
2.34.1