Messages in this thread | | | Subject | Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver | From | Dmitry Osipenko <> | Date | Mon, 6 Apr 2020 23:02:40 +0300 |
| |
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());
Is it really okay that list_empty() isn't protected with a lock?
Why wait_event is "interruptible"?
> + /* > + * 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; > + > + /* dequeue the buffer and start capture */ > + spin_lock(&chan->start_lock); > + if (list_empty(&chan->capture)) > + break; > + buf = list_entry(chan->capture.next, > + struct tegra_channel_buffer, queue);
list_first_entry()
> + list_del_init(&buf->queue); > + spin_unlock(&chan->start_lock); > + > + err = tegra_channel_capture_frame(chan, buf); > + if (err) > + vb2_queue_error(&chan->queue); > + } > + > + if (kthread_should_stop()) > + break; > + } > + > + return 0; > +}
| |