[PATCH v1 02/10] bus: mhi: core: Move to using high priority workqueue

[Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>]

MHI work is currently scheduled on the global/system workqueue and can
encounter delays on a stressed system. To avoid those unforeseen
delays which can hamper bootup or shutdown times, use a dedicated high
priority workqueue instead of the global/system workqueue.

Signed-off-by: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
---
 drivers/bus/mhi/core/init.c | 7 +++++++
 drivers/bus/mhi/core/pm.c   | 2 +-
 include/linux/mhi.h         | 2 ++
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index 1b4161e..ca32563 100644
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -890,6 +890,11 @@ int mhi_register_controller(struct mhi_controller *mhi_cntrl,
 	INIT_WORK(&mhi_cntrl->st_worker, mhi_pm_st_worker);
 	init_waitqueue_head(&mhi_cntrl->state_event);
 
+	mhi_cntrl->hiprio_wq = alloc_ordered_workqueue
+				("mhi_hiprio_wq", WQ_MEM_RECLAIM | WQ_HIGHPRI);
+	if (!mhi_cntrl->hiprio_wq)
+		goto error_alloc_cmd;
+
 	mhi_cmd = mhi_cntrl->mhi_cmd;
 	for (i = 0; i < NR_OF_CMD_RINGS; i++, mhi_cmd++)
 		spin_lock_init(&mhi_cmd->lock);
@@ -977,10 +982,12 @@ int mhi_register_controller(struct mhi_controller *mhi_cntrl,
 
 error_alloc_dev:
 	kfree(mhi_cntrl->mhi_cmd);
+	destroy_workqueue(mhi_cntrl->hiprio_wq);
 
 error_alloc_cmd:
 	vfree(mhi_cntrl->mhi_chan);
 	kfree(mhi_cntrl->mhi_event);
+	destroy_workqueue(mhi_cntrl->hiprio_wq);
 
 	return ret;
 }
diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index ce4d969..9d4789d 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -597,7 +597,7 @@ int mhi_queue_state_transition(struct mhi_controller *mhi_cntrl,
 	list_add_tail(&item->node, &mhi_cntrl->transition_list);
 	spin_unlock_irqrestore(&mhi_cntrl->transition_lock, flags);
 
-	schedule_work(&mhi_cntrl->st_worker);
+	queue_work(mhi_cntrl->hiprio_wq, &mhi_cntrl->st_worker);
 
 	return 0;
 }
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index fb45a0f..7677676 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -338,6 +338,7 @@ struct mhi_controller_config {
  * @wlock: Lock for protecting device wakeup
  * @mhi_link_info: Device bandwidth info
  * @st_worker: State transition worker
+ * @hiprio_wq: High priority workqueue
  * @state_event: State change event
  * @status_cb: CB function to notify power states of the device (required)
  * @wake_get: CB function to assert device wake (optional)
@@ -421,6 +422,7 @@ struct mhi_controller {
 	spinlock_t wlock;
 	struct mhi_link_info mhi_link_info;
 	struct work_struct st_worker;
+	struct workqueue_struct *hiprio_wq;
 	wait_queue_head_t state_event;
 
 	void (*status_cb)(struct mhi_controller *mhi_cntrl,
-- 
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