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Commit 6c0ffc67 authored by Guru Das Srinagesh's avatar Guru Das Srinagesh Committed by Subbaraman Narayanamurthy
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soc: altmode: Detect when remote subsys fails to respond 



The remote subsystem acknowledges all Altmode PMIC GLINK messages sent
to it. Print an error message anytime it fails to do this.

In the case when no client is found for a received message, do the
sending of the ack in a separate worker thread instead of a plain
function call to altmode_send_ack(). This is to avoid a deadlock and
consequent timing out in altmode_write(), which will happen in the
following scenario:
- A message is received for a nonexistent client.
- altmode_send_ack() is called from within altmode_callback().
- The PAN ACK is sent to the remote subsystem via pmic_glink_write() in
  altmode_write() and the remote subsystem replies with an ACK (opcode
  USBC_CMD_WRITE_REQ).
- Subsequently, in altmode_write() we wait for completion timeout, which
  will happen only if this new ACK message is processed by PMIC GLINK.
- PMIC GLINK is waiting for altmode_callback() to return so that it can
  process the new message.
- We are still waiting in altmode_callback() for altmode_send_ack() to
  complete.
- We time out in altmode_write() waiting for the completion to occur.

This problem is solved by firing off a worker thread to send the PAN ACK
so that altmode_callback() can exit quickly and allow the incoming new
ACK to hit the complete() in the USBC_CMD_WRITE_REQ case in
altmode_callback().

Also add a couple of minor fixes to some debug messages while we're at
it.

Change-Id: I3d80b1a7d6cc03b0eba61b5c9cc660ce7d377942
Signed-off-by: default avatarGuru Das Srinagesh <gurus@codeaurora.org>
parent fd62b366

drivers/soc/qcom/altmode-glink.c

+52 −10
Original line number Diff line number Diff line
@@ -55,7 +55,10 @@ struct usbc_write_buffer_req_msg { 
 * @client_list:	Linked list head keeping track of this device's clients

 * @pan_en_sent:	Flag to ensure PAN Enable msg is sent only once

 * @send_pan_en_work:	To schedule the sending of the PAN Enable message

 * @send_pan_ack_work:	To schedule the sending of the PAN Ack message

 * @debugfs_dir:	Dentry for debugfs directory "altmode"

 * @response_received:	To detect remote subsystem response failures

 * @ack_port_index:	Port index to ack for a nonexistent client

 */

struct altmode_dev {

	struct device			*dev;
@@ -66,7 +69,10 @@ struct altmode_dev { 
	struct list_head		client_list;

	atomic_t			pan_en_sent;

	struct delayed_work		send_pan_en_work;

	struct delayed_work		send_pan_ack_work;

	struct dentry			*debugfs_dir;

	struct completion		response_received;

	u8				ack_port_index;

};



/**
@@ -110,6 +116,8 @@ struct probe_notify_node { 
static LIST_HEAD(probe_notify_list);

static DEFINE_MUTEX(notify_lock);



static void altmode_send_pan_ack(struct work_struct *work);



static struct altmode_dev *to_altmode_device(struct device_node *amdev_node)

{

	struct platform_device *altmode_pdev;
@@ -121,10 +129,28 @@ static struct altmode_dev *to_altmode_device(struct device_node *amdev_node) 
	return NULL;

}



#define ALTMODE_WAIT_MS	1000

static int altmode_write(struct altmode_dev *amdev, void *data, size_t len)

{

	int rc;



	reinit_completion(&amdev->response_received);

	rc = pmic_glink_write(amdev->pgclient, data, len);

	if (!rc) {

		rc = wait_for_completion_timeout(&amdev->response_received,

				msecs_to_jiffies(ALTMODE_WAIT_MS));

		rc = rc ? 0 : -ETIMEDOUT;

	}



	if (rc)

		pr_err("Error in sending message: %d\n", rc);



	return rc;

}



static int __altmode_send_data(struct altmode_dev *amdev, void *data,

			       size_t len)

{

	int rc;

	struct usbc_write_buffer_req_msg msg = { { 0 } };



	if (len > sizeof(msg.buf)) {
@@ -139,11 +165,7 @@ static int __altmode_send_data(struct altmode_dev *amdev, void *data, 


	memcpy(msg.buf, data, len);



	rc = pmic_glink_write(amdev->pgclient, &msg, sizeof(msg));

	if (rc < 0)

		pr_err("Error in sending message: %d\n", rc);



	return rc;

	return altmode_write(amdev, &msg, sizeof(msg));

}



/**
@@ -433,11 +455,11 @@ static int altmode_send_ack(struct altmode_dev *amdev, u8 port_index) 


	rc = __altmode_send_data(amdev, &ack, sizeof(ack));

	if (rc < 0) {

		pr_err("port %u: Failed to send PAN ACK\n", port_index);

		pr_err("port %u: Failed to send PAN ACK: %d\n", port_index, rc);

		return rc;

	}



	pr_debug("port %d: Sent PAN ACK\n", port_index);

	pr_debug("port %u: Sent PAN ACK\n", port_index);



	return rc;

}
@@ -464,6 +486,14 @@ static void altmode_state_cb(void *priv, enum pmic_glink_state state) 
	}

}



static void altmode_send_pan_ack(struct work_struct *work)

{

	struct altmode_dev *amdev = container_of(work, struct altmode_dev,

			send_pan_ack_work.work);



	altmode_send_ack(amdev, amdev->ack_port_index);

}



#define USBC_NOTIFY_IND_MASK	GENMASK(7, 0)

#define GET_OP(opcode)		(opcode & USBC_NOTIFY_IND_MASK)

#define GET_SVID(opcode)	(opcode >> 16)
@@ -493,11 +523,17 @@ static int altmode_callback(void *priv, void *data, size_t len) 
	amclient = idr_find(&amdev->client_idr, IDR_KEY_GEN(svid, port_index));

	mutex_unlock(&amdev->client_lock);



	if (op == USBC_NOTIFY_IND) {

	switch (op) {

	case USBC_CMD_WRITE_REQ:

		complete(&amdev->response_received);

		break;

	case USBC_NOTIFY_IND:

		if (!amclient) {

			pr_debug("No client associated with SVID %#x port %u\n",

					svid, port_index);

			altmode_send_ack(amdev, port_index);

			amdev->ack_port_index = port_index;

			schedule_delayed_work(&amdev->send_pan_ack_work,

					msecs_to_jiffies(20));

			return 0;

		}
@@ -505,6 +541,9 @@ static int altmode_callback(void *priv, void *data, size_t len) 
				notify_msg->payload);

		amclient->data.callback(amclient->data.priv,

					notify_msg->payload, len);

		break;

	default:

		break;

	}



	return 0;
@@ -626,7 +665,9 @@ static int altmode_probe(struct platform_device *pdev) 


	mutex_init(&amdev->client_lock);

	idr_init(&amdev->client_idr);

	init_completion(&amdev->response_received);

	INIT_DELAYED_WORK(&amdev->send_pan_en_work, altmode_send_pan_en);

	INIT_DELAYED_WORK(&amdev->send_pan_ack_work, altmode_send_pan_ack);

	INIT_LIST_HEAD(&amdev->d_node);

	INIT_LIST_HEAD(&amdev->client_list);
@@ -675,6 +716,7 @@ static int altmode_remove(struct platform_device *pdev) 
	debugfs_remove_recursive(amdev->debugfs_dir);



	cancel_delayed_work_sync(&amdev->send_pan_en_work);

	cancel_delayed_work_sync(&amdev->send_pan_ack_work);

	idr_destroy(&amdev->client_idr);

	atomic_set(&amdev->pan_en_sent, 0);