From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [RFC PATCH v11 6/9] media: tegra: Add Tegra210 Video input driver Date: Thu, 30 Apr 2020 23:21:07 +0300 Message-ID: <8da0929d-4a58-75b8-381c-511ce66f8d9d@gmail.com> References: <1588197606-32124-1-git-send-email-skomatineni@nvidia.com> <1588197606-32124-7-git-send-email-skomatineni@nvidia.com> <52b98347-4b78-f637-04f4-cc730ad336f3@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <52b98347-4b78-f637-04f4-cc730ad336f3@nvidia.com> Content-Language: en-US Sender: linux-clk-owner@vger.kernel.org To: Sowjanya Komatineni , thierry.reding@gmail.com, jonathanh@nvidia.com, frankc@nvidia.com, hverkuil@xs4all.nl, sakari.ailus@iki.fi, helen.koike@collabora.com Cc: sboyd@kernel.org, linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-tegra@vger.kernel.org 30.04.2020 23:09, Sowjanya Komatineni пишет: > > On 4/30/20 1:08 PM, Sowjanya Komatineni wrote: >> >> On 4/30/20 1:06 PM, Dmitry Osipenko wrote: >>> 30.04.2020 01:00, 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; >>>> + >>>> +    set_freezable(); >>>> + >>>> +    while (1) { >>>> +        try_to_freeze(); >>>> + >>>> +        /* >>>> +         * Source is not streaming if error is non-zero. >>>> +         * So, do not dequeue buffers on error and let the thread >>>> sleep >>>> +         * till kthread stop signal is received. >>>> +         */ >>>> +        wait_event_interruptible(chan->start_wait, >>>> +                     kthread_should_stop() || >>>> +                     (!list_empty(&chan->capture) && >>>> +                     !err)); >>> ... >>>> +static void tegra_channel_buffer_queue(struct vb2_buffer *vb) >>>> +{ >>>> +    struct tegra_vi_channel *chan = vb2_get_drv_priv(vb->vb2_queue); >>>> +    struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb); >>>> +    struct tegra_channel_buffer *buf = to_tegra_channel_buffer(vbuf); >>>> + >>>> +    /* put buffer into the capture queue */ >>>> +    spin_lock(&chan->start_lock); >>>> +    list_add_tail(&buf->queue, &chan->capture); >>>> +    spin_unlock(&chan->start_lock); >>>> + >>>> +    /* wait up kthread for capture */ >>>> +    wake_up_interruptible(&chan->start_wait); >>>> +} >>> The V4L doc says that buffers could be enqueued before streaming is >>> started. I guess it should be a trouble here, shouldn't it? >>> >>> https://elixir.bootlin.com/linux/v5.7-rc3/source/include/media/videobuf2-core.h#L379 >>> >> >> what trouble are you referring here? >> >> I dont think so as we set min buffers needed as 2 always there will be >> 2 per-queued buffers. > typo* pre-queued buffers before streaming start >> >> But buffers from this queue will be dequeued only when ready to >> processes in the capture thread I see now that the threads won't be running until start_streaming() is invoked, should be okay then.