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<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> <0c425505-347f-7418-af7e-d121fe0d06dc@nvidia.com> <1a31cd60-739f-0660-1c45-31487d2f2128@nvidia.com> Message-ID: <603084a5-249a-4fe2-3646-e9335ef9ab43@nvidia.com> Date: Tue, 7 Apr 2020 16:38:07 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <1a31cd60-739f-0660-1c45-31487d2f2128@nvidia.com> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To DRHQMAIL107.nvidia.com (10.27.9.16) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Content-Language: en-US DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1586302588; bh=X8IJFWDnQAbnf1aSpLJmy4TiOpGQ753NFIkPWM15bII=; h=X-PGP-Universal:Subject:From:To:CC:References:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Transfer-Encoding: Content-Language; b=G4QUu/SWOKZrVd9ZdM8wMOi4dimJpCxB55TLA8YWXoMwreB64M4HhIW8FjAQyXx4J YZzkqbDWP+nkEsL6W03TUKutts/HBpsJyLt1lxAsHRCgEvI1mTpUGpNf8nIwRjqACi 9Cj2GejpW9ZmcWPZpFc09Al1qRRKcpJ6wfvGX8puwTywyZ+eWYVwSQNsxV/tJHBcJr HHzRZykCtlqUMhpH089DpBCia375rPeGkFB0cF0bQCVfBPcu2UBnE1ldAKIWDfUJwb 1KGSlwap9yygrXYa0BORKSZa2cAbq0L2AY3/T0Foq0IfBibmIlJrG0Ja/a8KBVsPgX J7kx9aK/A09lQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/7/20 4:36 PM, Sowjanya Komatineni wrote: > > On 4/7/20 4:12 PM, Dmitry Osipenko wrote: >> External email: Use caution opening links or attachments >> >> >> 08.04.2020 01:22, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>> 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=20 >>>>>> and it >>>>>> continues only after fifo has min 1 slot empty >>>>> Just want to close on this part of feedback. Hope above=20 >>>>> explanation is >>>>> clear regarding triggering/issuing at max 2 frame capture to VI HW=20 >>>>> and >>>>> also regarding capture threads where they use=20 >>>>> 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. >>>> =C2=A0 From what I see in the code, you "hold on" by making kthread to= =20 >>>> 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 >>> capture so as soon as VI HW issuing single shot is done and when min 1 >>> slot is empty we should continue with issuing for another capture. >>> >>> As long as buffers are available, we should continue to capture and >>> should not hold >>> >> I suppose that taking a shot takes at least few milliseconds, which >> should be unacceptable to waste. > As long as buffers are in queue we have to keep processing each buffer=20 > and between buffers obviously we have to wait for previous frames to=20 > finish and this why we have separate thread for frame finish where we=20 > can have next buffer capture ready and issue while previous frame=20 > memory write happens