Messages in this thread | | | Subject | Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver | From | Sowjanya Komatineni <> | Date | Mon, 6 Apr 2020 13:55:12 -0700 |
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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
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