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media: v4l2-mem2mem: Fix missing v4l2_m2m_try_run call 

Commit 34dbb848d5 ("media: mem2mem: Remove excessive try_run call")
removed a redundant call to v4l2_m2m_try_run but instead introduced
a bug. Consider the following case:

 1) Context A schedules, queues and runs job A.
 2) While the m2m device is running, context B schedules
    and queues job B. Job B cannot run, because it has to
    wait for job A.
 3) Job A completes, calls v4l2_m2m_job_finish, and tries
    to queue a job for context A, but since the context is
    empty it won't do anything.

In this scenario, queued job B will never run. Fix this by calling
v4l2_m2m_try_run from v4l2_m2m_try_schedule.

While here, add more documentation to these functions.

Fixes: 34dbb848d5 ("media: mem2mem: Remove excessive try_run call")

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
[hans.verkuil@cisco.com: split >80 cols line]
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Ezequiel Garcia 2018-07-25 13:15:12 -04:00 committed by Mauro Carvalho Chehab
parent 39dd23dc9d
commit 9db3bbf58b
1 changed files with 30 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
drivers/media/v4l2-core/v4l2-mem2mem.c
View File

@ -249,15 +249,24 @@ static void v4l2_m2m_try_run(struct v4l2_m2m_dev *m2m_dev)
m2m_dev->curr_ctx->job_flags |= TRANS_RUNNING;
spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
dprintk("Running job on m2m_ctx: %p\n", m2m_dev->curr_ctx);
m2m_dev->m2m_ops->device_run(m2m_dev->curr_ctx->priv);
}
void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx)
/*
* __v4l2_m2m_try_queue() - queue a job
* @m2m_dev: m2m device
* @m2m_ctx: m2m context
*
* Check if this context is ready to queue a job.
*
* This function can run in interrupt context.
*/
static void __v4l2_m2m_try_queue(struct v4l2_m2m_dev *m2m_dev,
struct v4l2_m2m_ctx *m2m_ctx)
{
struct v4l2_m2m_dev *m2m_dev;
unsigned long flags_job, flags_out, flags_cap;
m2m_dev = m2m_ctx->m2m_dev;
dprintk("Trying to schedule a job for m2m_ctx: %p\n", m2m_ctx);
if (!m2m_ctx->out_q_ctx.q.streaming
@ -315,7 +324,25 @@ void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx)
m2m_ctx->job_flags |= TRANS_QUEUED;
spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
}
/**
* v4l2_m2m_try_schedule() - schedule and possibly run a job for any context
* @m2m_ctx: m2m context
*
* Check if this context is ready to queue a job. If suitable,
* run the next queued job on the mem2mem device.
*
* This function shouldn't run in interrupt context.
*
* Note that v4l2_m2m_try_schedule() can schedule one job for this context,
* and then run another job for another context.
*/
void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx)
{
struct v4l2_m2m_dev *m2m_dev = m2m_ctx->m2m_dev;
__v4l2_m2m_try_queue(m2m_dev, m2m_ctx);
v4l2_m2m_try_run(m2m_dev);
}
EXPORT_SYMBOL_GPL(v4l2_m2m_try_schedule);