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[91.78.208.152]) by smtp.googlemail.com with ESMTPSA id z9sm663609lfd.9.2020.04.30.13.06.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Apr 2020 13:06:17 -0700 (PDT) Subject: Re: [RFC PATCH v11 6/9] media: tegra: Add Tegra210 Video input driver 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 References: <1588197606-32124-1-git-send-email-skomatineni@nvidia.com> <1588197606-32124-7-git-send-email-skomatineni@nvidia.com> From: Dmitry Osipenko Message-ID: Date: Thu, 30 Apr 2020 23:06:15 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <1588197606-32124-7-git-send-email-skomatineni@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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