From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sowjanya Komatineni Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver Date: Tue, 7 Apr 2020 15:22:05 -0700 Message-ID: <0c425505-347f-7418-af7e-d121fe0d06dc@nvidia.com> References: <1585963507-12610-1-git-send-email-skomatineni@nvidia.com> <1585963507-12610-7-git-send-email-skomatineni@nvidia.com> <200bb96e-2d07-764f-9e14-55538dc742fd@gmail.com> <23bfab09-b464-6e51-9843-06d13000e9b9@nvidia.com> <08cd31d5-e8b9-4d3a-fb0e-0e4462947d96@nvidia.com> <12a834ac-52b1-6dc0-7d3a-3e6a1fa85a2a@gmail.com> <760d071e-0cbc-b3eb-9231-fb9f9ecb44a6@nvidia.com> <9e317f65-8a02-3b15-cfec-8e0d8374130e@gmail.com> <97b35910-4c93-123a-43a0-eb14476ed0f3@nvidia.com> <84ad4e2d-6ac1-e1f4-1c55-5edaae850631@nvidia.com> <15a879b3-8fb9-6821-3cdc-104ba583ac12@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <15a879b3-8fb9-6821-3cdc-104ba583ac12@gmail.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Dmitry Osipenko , 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 On 4/7/20 3:08 PM, Dmitry Osipenko wrote: > External email: Use caution opening links or attachments > > > 08.04.2020 00:08, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > ... >>>> I think you need a semaphore with resource count =3D 2. >>> we hold on to issuing capture if more than 2 buffers are queued and it >>> continues only after fifo has min 1 slot empty >> >> Just want to close on this part of feedback. Hope above explanation is >> clear regarding triggering/issuing at max 2 frame capture to VI HW and >> also regarding capture threads where they use wait_event_interruptible >> to prevent blocking waiting for buffers to be available for captures. >> >> So no changes related to this part are needed in v7. > From what I see in the code, you "hold on" by making kthread to spin in > a busy-loop while caps_inflight >=3D SYNCPT_FIFO_DEPTH. So some change > should be needed to prevent this. > > The wait_event_interruptible seems should be okay. We don't want to prevent that as we already have buffers available for=20 capture so as soon as VI HW issuing single shot is done and when min 1=20 slot is empty we should continue with issuing for another capture. As long as buffers are available, we should continue to capture and=20 should not hold