[RFC PATCH V4 1/4] media: v4l2-mem2mem: add v4l2_m2m_suspend, v4l2_m2m_resume

[Jerry-ch Chen <Jerry-Ch.chen@mediatek.com>]

From: Pi-Hsun Shih <pihsun@chromium.org>

Add two functions that can be used to stop new jobs from being queued /
continue running queued job. This can be used while a driver using m2m
helper is going to suspend / wake up from resume, and can ensure that
there's no job running in suspend process.

BUG=b:143046833
TEST=build

Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
Signed-off-by: Jerry-ch Chen <jerry-ch.chen@mediatek.corp-partner.google.com>
---
 drivers/media/v4l2-core/v4l2-mem2mem.c | 40 ++++++++++++++++++++++++++
 include/media/v4l2-mem2mem.h           | 22 ++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
index 5bbdec55b7d7..76ba203e0035 100644
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -47,6 +47,10 @@ module_param(debug, bool, 0644);
 #define TRANS_ABORT		(1 << 2)
 
 
+/* The job queue is not running new jobs */
+#define QUEUE_PAUSED		(1 << 0)
+
+
 /* Offset base for buffers on the destination queue - used to distinguish
  * between source and destination buffers when mmapping - they receive the same
  * offsets but for different queues */
@@ -88,6 +92,7 @@ static const char * const m2m_entity_name[] = {
  * @job_queue:		instances queued to run
  * @job_spinlock:	protects job_queue
  * @job_work:		worker to run queued jobs.
+ * @job_queue_flags:	flags of the queue status, %QUEUE_PAUSED.
  * @m2m_ops:		driver callbacks
  */
 struct v4l2_m2m_dev {
@@ -105,6 +110,7 @@ struct v4l2_m2m_dev {
 	struct list_head	job_queue;
 	spinlock_t		job_spinlock;
 	struct work_struct	job_work;
+	unsigned long		job_queue_flags;
 
 	const struct v4l2_m2m_ops *m2m_ops;
 };
@@ -267,6 +273,12 @@ static void v4l2_m2m_try_run(struct v4l2_m2m_dev *m2m_dev)
 		return;
 	}
 
+	if (m2m_dev->job_queue_flags & QUEUE_PAUSED) {
+		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
+		dprintk("Running new jobs is paused\n");
+		return;
+	}
+
 	m2m_dev->curr_ctx = list_first_entry(&m2m_dev->job_queue,
 				   struct v4l2_m2m_ctx, queue);
 	m2m_dev->curr_ctx->job_flags |= TRANS_RUNNING;
@@ -447,6 +459,34 @@ void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
 }
 EXPORT_SYMBOL(v4l2_m2m_job_finish);
 
+void v4l2_m2m_suspend(struct v4l2_m2m_dev *m2m_dev)
+{
+	unsigned long flags;
+	struct v4l2_m2m_ctx *curr_ctx;
+
+	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
+	m2m_dev->job_queue_flags |= QUEUE_PAUSED;
+	curr_ctx = m2m_dev->curr_ctx;
+	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
+
+	if (curr_ctx)
+		wait_event(curr_ctx->finished,
+			   !(curr_ctx->job_flags & TRANS_RUNNING));
+}
+EXPORT_SYMBOL(v4l2_m2m_suspend);
+
+void v4l2_m2m_resume(struct v4l2_m2m_dev *m2m_dev)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
+	m2m_dev->job_queue_flags &= ~QUEUE_PAUSED;
+	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
+
+	v4l2_m2m_try_run(m2m_dev);
+}
+EXPORT_SYMBOL(v4l2_m2m_resume);
+
 int v4l2_m2m_reqbufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 		     struct v4l2_requestbuffers *reqbufs)
 {
diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index 5467264771ec..119a195da390 100644
--- a/include/media/v4l2-mem2mem.h
+++ b/include/media/v4l2-mem2mem.h
@@ -183,6 +183,28 @@ v4l2_m2m_buf_done(struct vb2_v4l2_buffer *buf, enum vb2_buffer_state state)
 	vb2_buffer_done(&buf->vb2_buf, state);
 }
 
+/**
+ * v4l2_m2m_suspend() - stop new jobs from being run and wait for current job
+ * to finish
+ *
+ * @m2m_dev: opaque pointer to the internal data to handle M2M context
+ *
+ * Called by a driver in the suspend hook. Stop new jobs from being run, and
+ * wait for current running job to finish.
+ */
+void v4l2_m2m_suspend(struct v4l2_m2m_dev *m2m_dev);
+
+/**
+ * v4l2_m2m_resume() - resume job running and try to run a queued job
+ *
+ * @m2m_dev: opaque pointer to the internal data to handle M2M context
+ *
+ * Called by a driver in the resume hook. This reverts the operation of
+ * v4l2_m2m_suspend() and allows job to be run. Also try to run a queued job if
+ * there is any.
+ */
+void v4l2_m2m_resume(struct v4l2_m2m_dev *m2m_dev);
+
 /**
  * v4l2_m2m_reqbufs() - multi-queue-aware REQBUFS multiplexer
  *
-- 
2.18.0
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