<div dir="ltr"><div>Hi,</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, May 18, 2019 at 4:14 AM Niklas Söderlund <<a href="mailto:niklas.soderlund%2Brenesas@ragnatech.se">niklas.soderlund+renesas@ragnatech.se</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Prepare for multiple video streams from the same sensor by serializing<br>
vimc_streamer_s_stream(). Multiple streams will allow for multiple<br>
concurrent calls to this function that could involve the same<br>
subdevices.<br>
<br>
If that happens the internal state of the involved subdevices could go<br>
out of sync as they are being started and stopped at the same time,<br>
prevent this by serializing starting and stopping of the vimc streamer.<br>
<br>
Signed-off-by: Niklas Söderlund <<a href="mailto:niklas.soderlund@ragnatech.se" target="_blank">niklas.soderlund@ragnatech.se</a>><br>
---<br>
 drivers/media/platform/vimc/vimc-streamer.c | 23 ++++++++++++++-------<br>
 1 file changed, 16 insertions(+), 7 deletions(-)<br>
<br>
diff --git a/drivers/media/platform/vimc/vimc-streamer.c b/drivers/media/platform/vimc/vimc-streamer.c<br>
index 26b6742594890b16..514690dca3b1187b 100644<br>
--- a/drivers/media/platform/vimc/vimc-streamer.c<br>
+++ b/drivers/media/platform/vimc/vimc-streamer.c<br>
@@ -153,39 +153,48 @@ int vimc_streamer_s_stream(struct vimc_stream *stream,<br>
                           struct vimc_ent_device *ved,<br>
                           int enable)<br>
 {<br>
+       static DEFINE_MUTEX(vimc_streamer_lock);<br></blockquote><div>This is unusual to have static global in a function, maybe better declare it outside the function.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
        int ret;<br>
<br>
        if (!stream || !ved)<br>
                return -EINVAL;<br>
<br>
+       ret = mutex_lock_interruptible(&vimc_streamer_lock);<br>
+       if (ret)<br>
+               return ret;<br>
+<br>
        if (enable) {<br>
                if (stream->kthread)<br>
-                       return 0;<br>
+                       goto out;<br>
<br>
                ret = vimc_streamer_pipeline_init(stream, ved);<br>
                if (ret)<br>
-                       return ret;<br>
+                       goto out;<br>
<br>
                stream->kthread = kthread_run(vimc_streamer_thread, stream,<br>
                                              "vimc-streamer thread");<br>
<br>
-               if (IS_ERR(stream->kthread))<br>
-                       return PTR_ERR(stream->kthread);<br>
+               if (IS_ERR(stream->kthread)) {<br>
+                       ret = PTR_ERR(stream->kthread);<br>
+                       goto out;<br>
+               }<br>
<br>
        } else {<br>
                if (!stream->kthread)<br>
-                       return 0;<br>
+                       goto out;<br>
<br>
                ret = kthread_stop(stream->kthread);<br>
                if (ret)<br>
-                       return ret;<br>
+                       goto out;<br>
<br>
                stream->kthread = NULL;<br>
<br>
                vimc_streamer_pipeline_terminate(stream);<br>
        }<br>
+out:<br>
+       mutex_unlock(&vimc_streamer_lock);<br>
<br>
-       return 0;<br>
+       return ret;<br>
 }<br>
 EXPORT_SYMBOL_GPL(vimc_streamer_s_stream);<br>
<br></blockquote><div><br></div><div>The frame allocated by each vimc entity  is the same frame for all streaming threads, </div><div>isn't access to the frame should also be serialized?</div><div><br></div><div>Thanks,</div><div>Dafna</div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
-- <br>
2.21.0<br>
<br>
</blockquote></div></div>