linux-kernel - [PATCH 2/4 v6] memstick: Prevent memstick host from getting runtime suspended during card detection

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Date:   Wed, 31 Oct 2018 14:59:01 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     arnd@...db.de, gregkh@...uxfoundation.org
Cc:     ulf.hansson@...aro.org, stern@...land.harvard.edu,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>
Subject: [PATCH 2/4 v6] memstick: Prevent memstick host from getting runtime suspended during card detection

We can use MEMSTICK_POWER_{ON,OFF} along with pm_runtime_{get,put}
helpers to let memstick host support runtime pm.

The rpm count may go down to zero before the memstick host powers on, so
the host can be runtime suspended.

So before doing card detection, increment the rpm count to avoid the
host gets runtime suspended. Balance the rpm count after card detection
is done.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
 drivers/memstick/core/memstick.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c
index 76382c858c35..1246d69ba187 100644
--- a/drivers/memstick/core/memstick.c
+++ b/drivers/memstick/core/memstick.c
@@ -18,6 +18,7 @@
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <linux/pm_runtime.h>
 
 #define DRIVER_NAME "memstick"
 
@@ -436,6 +437,7 @@ static void memstick_check(struct work_struct *work)
 	struct memstick_dev *card;
 
 	dev_dbg(&host->dev, "memstick_check started\n");
+	pm_runtime_get_noresume(host->dev.parent);
 	mutex_lock(&host->lock);
 	if (!host->card) {
 		if (memstick_power_on(host))
@@ -479,6 +481,7 @@ static void memstick_check(struct work_struct *work)
 		host->set_param(host, MEMSTICK_POWER, MEMSTICK_POWER_OFF);
 
 	mutex_unlock(&host->lock);
+	pm_runtime_put(host->dev.parent);
 	dev_dbg(&host->dev, "memstick_check finished\n");
 }
 
-- 
2.17.1