Commit 8530e4e2 authored by Heikki Krogerus's avatar Heikki Krogerus Committed by Greg Kroah-Hartman
Browse files

usb: typec: ucsi: ccg: Remove run_isr flag 



The "run_isr" flag is used for preventing the driver from
calling the interrupt service routine in its runtime resume
callback when the driver is expecting completion to a
command, but what that basically does is that it hides the
real problem. The real problem is that the controller is
allowed to suspend in the middle of command execution.

As a more appropriate fix for the problem, using autosuspend
delay time that matches UCSI_TIMEOUT_MS (5s). That prevents
the controller from suspending while still in the middle of
executing a command.

This fixes a potential deadlock. Both ccg_read() and
ccg_write() are called with the mutex already taken at least
from ccg_send_command(). In ccg_read() and ccg_write, the
mutex is only acquired so that run_isr flag can be set.

Fixes: f0e4cd94 ("usb: typec: ucsi: ccg: add runtime pm workaround")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20191004100219.71152-2-heikki.krogerus@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c9a2baa7

drivers/usb/typec/ucsi/ucsi_ccg.c

+4 −38
Original line number Diff line number Diff line
@@ -195,7 +195,6 @@ struct ucsi_ccg { 


	/* fw build with vendor information */

	u16 fw_build;

	bool run_isr; /* flag to call ISR routine during resume */

	struct work_struct pm_work;

};
@@ -224,18 +223,6 @@ static int ccg_read(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len) 
	if (quirks && quirks->max_read_len)

		max_read_len = quirks->max_read_len;



	if (uc->fw_build == CCG_FW_BUILD_NVIDIA &&

	    uc->fw_version <= CCG_OLD_FW_VERSION) {

		mutex_lock(&uc->lock);

		/*

		 * Do not schedule pm_work to run ISR in

		 * ucsi_ccg_runtime_resume() after pm_runtime_get_sync()

		 * since we are already in ISR path.

		 */

		uc->run_isr = false;

		mutex_unlock(&uc->lock);

	}



	pm_runtime_get_sync(uc->dev);

	while (rem_len > 0) {

		msgs[1].buf = &data[len - rem_len];
@@ -278,18 +265,6 @@ static int ccg_write(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len) 
	msgs[0].len = len + sizeof(rab);

	msgs[0].buf = buf;



	if (uc->fw_build == CCG_FW_BUILD_NVIDIA &&

	    uc->fw_version <= CCG_OLD_FW_VERSION) {

		mutex_lock(&uc->lock);

		/*

		 * Do not schedule pm_work to run ISR in

		 * ucsi_ccg_runtime_resume() after pm_runtime_get_sync()

		 * since we are already in ISR path.

		 */

		uc->run_isr = false;

		mutex_unlock(&uc->lock);

	}



	pm_runtime_get_sync(uc->dev);

	status = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));

	if (status < 0) {
@@ -1130,7 +1105,6 @@ static int ucsi_ccg_probe(struct i2c_client *client, 
	uc->ppm.sync = ucsi_ccg_sync;

	uc->dev = dev;

	uc->client = client;

	uc->run_isr = true;

	mutex_init(&uc->lock);

	INIT_WORK(&uc->work, ccg_update_firmware);

	INIT_WORK(&uc->pm_work, ccg_pm_workaround_work);
@@ -1188,6 +1162,8 @@ static int ucsi_ccg_probe(struct i2c_client *client, 


	pm_runtime_set_active(uc->dev);

	pm_runtime_enable(uc->dev);

	pm_runtime_use_autosuspend(uc->dev);

	pm_runtime_set_autosuspend_delay(uc->dev, 5000);

	pm_runtime_idle(uc->dev);



	return 0;
@@ -1229,7 +1205,6 @@ static int ucsi_ccg_runtime_resume(struct device *dev) 
{

	struct i2c_client *client = to_i2c_client(dev);

	struct ucsi_ccg *uc = i2c_get_clientdata(client);

	bool schedule = true;



	/*

	 * Firmware version 3.1.10 or earlier, built for NVIDIA has known issue
@@ -1237,17 +1212,8 @@ static int ucsi_ccg_runtime_resume(struct device *dev) 
	 * Schedule a work to call ISR as a workaround.

	 */

	if (uc->fw_build == CCG_FW_BUILD_NVIDIA &&

	    uc->fw_version <= CCG_OLD_FW_VERSION) {

		mutex_lock(&uc->lock);

		if (!uc->run_isr) {

			uc->run_isr = true;

			schedule = false;

		}

		mutex_unlock(&uc->lock);



		if (schedule)

	    uc->fw_version <= CCG_OLD_FW_VERSION)

		schedule_work(&uc->pm_work);

	}



	return 0;

}

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