[PATCH] Do some changes in mmc core layer to enable mmc card runtime pm.

[Yunpeng Gao]

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.

Signed-off-by: Yunpeng Gao <yunpeng.gao@xxxxxxxxx>
---
 drivers/mmc/core/core.c |    4 ++++
 drivers/mmc/core/host.c |    3 +++
 2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 6286898..2905dac 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -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);
 }
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 92e3370..caa9e85 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/