Re: [RFC PATCH v11 6/9] media: tegra: Add Tegra210 Video input driver

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On 4/30/20 7:13 AM, Dmitry Osipenko wrote:
30.04.2020 17:02, Dmitry Osipenko пишет:
30.04.2020 16:56, Dmitry Osipenko пишет:
30.04.2020 01:00, Sowjanya Komatineni пишет:
+static int chan_capture_kthread_finish(void *data)
+{
+	struct tegra_vi_channel *chan = data;
+	struct tegra_channel_buffer *buf;
+
+	set_freezable();
+
+	while (1) {
+		try_to_freeze();
I guess it won't be great to freeze in the middle of a capture process, so:
		if (list_empty(&chan->done))
			try_to_freeze();
And here should be some locking protection in order not race with the
chan_capture_kthread_start because kthread_finish could freeze before
kthread_start.
Or maybe both start / finish threads should simply be allowed to freeze
only when both capture and done lists are empty.

if (list_empty(&chan->capture) &&
     list_empty(&chan->done))
	try_to_freeze();

good to freeze when not in middle of the frame capture but why should we not allow freeze in between captures?

Other drivers do allow freeze in between frame captures.

I guess we can freeze before dequeue for capture and in finish thread we can freeze after capture done. This also don't need to check for list_empty with freeze to allow between frame captures.






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