mmc: changes to enable runtime PM of mmc core layer

From: Yunpeng Gao <[email protected]>
Date: Mon, 6 Dec 2010 20:03:00 +0800
Subject: [PATCH] Do some changes in mmc core layer to enable mmc card runtime pm.

Seems current runtime PM support in mmc core layer has some problems:

1. If host controller is PCI device, then it's possibly that the PCI host controller will be runtime suspended immediately after its PCI probe. Then it will have trouble when do the following mmc_rescan since at that time the function driver (mmc block driver or sdio function driver) has not been called and there's no chance to execute pm_runtime_get().

2. Currently mmc_host_class (defined in drivers/mmc/core/host.c) is parent of mmc_card and child of host controller. But mmc_host_class has not implemented the runtime pm APIs of itself. So seems it'll cause the mmc runtime PM chain disconnect here.

This patch tries to fix above 2 problems.
For 1, it adds pm_runtime_get/put at the begging/end of function mmc_rescan().
For2, it calling the pm_runtime_no_callbacks() API to bypass the mmc_host_class device.

---
 drivers/mmc/core/core.c |    4 ++++
 drivers/mmc/core/host.c |    3 +++
 2 files changed, 7 insertions(+), 0 deletions(-)

index 6286898..2905dac 100644
@@ -22,6 +22,7 @@
 #include <linux/scatterlist.h>
 #include <linux/log2.h>
 #include <linux/regulator/consumer.h>
+#include <linux/pm_runtime.h>
 
 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>

@@ -1503,6 +1504,7 @@ void mmc_rescan(struct work_struct *work)
 
 	spin_unlock_irqrestore(&host->lock, flags);
 
+	pm_runtime_get_sync(host->parent);
 
 	mmc_bus_get(host);
 

@@ -1598,6 +1600,8 @@ out_fail:
 		mmc_power_off(host);
 	}
 out:
+	pm_runtime_put_sync(host->parent);
+
 	if (host->caps & MMC_CAP_NEEDS_POLL)
 		mmc_schedule_delayed_work(&host->detect, HZ);
 }

index 92e3370..caa9e85 100644
@@ -19,6 +19,7 @@
 #include <linux/leds.h>
 #include <linux/slab.h>
 #include <linux/suspend.h>
+#include <linux/pm_runtime.h>
 
 #include <linux/mmc/host.h>
 #include <linux/mmc/card.h>

@@ -303,6 +304,8 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
 	host->max_blk_size = 512;
 	host->max_blk_count = PAGE_CACHE_SIZE / 512;
 
+	pm_runtime_no_callbacks(&host->class_dev);
+
 	return host;
 
 free:

1.6.6.1