linux-kernel - [char-misc-next] mei: speed up the power down flow

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Date:   Tue, 12 Dec 2017 13:27:06 +0200
From:   Tomas Winkler <tomas.winkler@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Alexander Usyskin <alexander.usyskin@...el.com>,
        linux-kernel@...r.kernel.org,
        Tomas Winkler <tomas.winkler@...el.com>
Subject: [char-misc-next] mei: speed up the power down flow

When mei driver is powering down due to suspend or shutdown
it will iterate over the mei client bus and disconnect
each client device attached in turn.
The power down flow consist of the link rest, which causes all clients
get disconnected at once, hence the individual disconnection
can be omitted and significantly reduce power down flow.

Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
---
 drivers/misc/mei/bus.c    | 10 ++++++++--
 drivers/misc/mei/hw-me.c  |  4 +++-
 drivers/misc/mei/hw-txe.c |  4 +++-
 drivers/misc/mei/init.c   |  4 +++-
 4 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index 1ac10cb64d6e..2a5146bdecf1 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -543,14 +543,20 @@ int mei_cldev_disable(struct mei_cl_device *cldev)
 	mutex_lock(&bus->device_lock);
 
 	if (!mei_cl_is_connected(cl)) {
-		dev_dbg(bus->dev, "Already disconnected");
+		dev_dbg(bus->dev, "Already disconnected\n");
+		err = 0;
+		goto out;
+	}
+
+	if (bus->dev_state == MEI_DEV_POWER_DOWN) {
+		dev_dbg(bus->dev, "Device is powering down don't botther with disconnection\n");
 		err = 0;
 		goto out;
 	}
 
 	err = mei_cl_disconnect(cl);
 	if (err < 0)
-		dev_err(bus->dev, "Could not disconnect from the ME client");
+		dev_err(bus->dev, "Could not disconnect from the ME client\n");
 
 out:
 	/* Flush queues and remove any pending read */
diff --git a/drivers/misc/mei/hw-me.c b/drivers/misc/mei/hw-me.c
index 10dcf4ff99a5..0b21f9ec00f5 100644
--- a/drivers/misc/mei/hw-me.c
+++ b/drivers/misc/mei/hw-me.c
@@ -1260,7 +1260,9 @@ irqreturn_t mei_me_irq_thread_handler(int irq, void *dev_id)
 		if (rets == -ENODATA)
 			break;
 
-		if (rets && dev->dev_state != MEI_DEV_RESETTING) {
+		if (rets &&
+		    (dev->dev_state != MEI_DEV_RESETTING ||
+		     dev->dev_state != MEI_DEV_POWER_DOWN)) {
 			dev_err(dev->dev, "mei_irq_read_handler ret = %d.\n",
 						rets);
 			schedule_work(&dev->reset_work);
diff --git a/drivers/misc/mei/hw-txe.c b/drivers/misc/mei/hw-txe.c
index 24e4a4c96606..84197277f26c 100644
--- a/drivers/misc/mei/hw-txe.c
+++ b/drivers/misc/mei/hw-txe.c
@@ -1127,7 +1127,9 @@ irqreturn_t mei_txe_irq_thread_handler(int irq, void *dev_id)
 	if (test_and_clear_bit(TXE_INTR_OUT_DB_BIT, &hw->intr_cause)) {
 		/* Read from TXE */
 		rets = mei_irq_read_handler(dev, &cmpl_list, &slots);
-		if (rets && dev->dev_state != MEI_DEV_RESETTING) {
+		if (rets &&
+		    (dev->dev_state != MEI_DEV_RESETTING ||
+		     dev->dev_state != MEI_DEV_POWER_DOWN)) {
 			dev_err(dev->dev,
 				"mei_irq_read_handler ret = %d.\n", rets);
 
diff --git a/drivers/misc/mei/init.c b/drivers/misc/mei/init.c
index d2f691424dd1..c46f6e99a55e 100644
--- a/drivers/misc/mei/init.c
+++ b/drivers/misc/mei/init.c
@@ -310,6 +310,9 @@ void mei_stop(struct mei_device *dev)
 {
 	dev_dbg(dev->dev, "stopping the device.\n");
 
+	mutex_lock(&dev->device_lock);
+	dev->dev_state = MEI_DEV_POWER_DOWN;
+	mutex_unlock(&dev->device_lock);
 	mei_cl_bus_remove_devices(dev);
 
 	mei_cancel_work(dev);
@@ -319,7 +322,6 @@ void mei_stop(struct mei_device *dev)
 
 	mutex_lock(&dev->device_lock);
 
-	dev->dev_state = MEI_DEV_POWER_DOWN;
 	mei_reset(dev);
 	/* move device to disabled state unconditionally */
 	dev->dev_state = MEI_DEV_DISABLED;
-- 
2.14.3