On 4/6/20 1:56 PM, Dmitry Osipenko wrote:
External email: Use caution opening links or attachments
06.04.2020 23:55, Sowjanya Komatineni пишет:
On 4/6/20 1:53 PM, Dmitry Osipenko wrote:
External email: Use caution opening links or attachments
06.04.2020 23:50, Sowjanya Komatineni пишет:
On 4/6/20 1:45 PM, Dmitry Osipenko wrote:
External email: Use caution opening links or attachments
04.04.2020 04:25, Sowjanya Komatineni пишет:
+static int chan_capture_kthread_start(void *data)
+{
+ struct tegra_vi_channel *chan = data;
+ struct tegra_channel_buffer *buf;
+ int err = 0;
+ int caps_inflight;
+
+ set_freezable();
+
+ while (1) {
+ try_to_freeze();
+
+ wait_event_interruptible(chan->start_wait,
+ !list_empty(&chan->capture) ||
+ kthread_should_stop());
+ /*
+ * Frame start and MW_ACK_DONE syncpoint condition
FIFOs are
+ * of max depth 2. So make sure max 2 capture
requests are
+ * in process by the hardware at a time.
+ */
+ while (!(kthread_should_stop() ||
list_empty(&chan->capture))) {
+ caps_inflight = chan->capture_reqs -
chan->sequence;
+ /*
+ * Source is not streaming if error is non-zero.
+ * So, do not dequeue buffers on capture error
or when
+ * syncpoint requests in FIFO are full.
+ */
+ if (err || caps_inflight >= SYNCPT_FIFO_DEPTH)
+ break;
Am I understanding correctly that this thread will take 100% CPU,
spinning here, if more than 2 frame-captures queued?
on more than 2 frames captures, it breaks thread and on next wakeup it
continues
The wait_event() won't wait if condition is true.
condition is checked when waitqueue is woken up
https://elixir.bootlin.com/linux/v5.6.2/source/include/linux/wait.h#L462
process is put to sleep until the condition evaluates to true or signal
is received.
condition is checked each time the waitqueue head is woken up.
Also capture list may keep on getting updated with buffers from userspace.
but at a time we only limit 2 frames as VI supports double buffering and
syncpt fifo's max depth is 2
Any more buffers waiting will be processing on subsequent iterations.
So basically thread run time is depending on buffers getting queued from
userspace.
