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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> <603084a5-249a-4fe2-3646-e9335ef9ab43@nvidia.com> <7895b9c6-f27d-8939-73d7-67d785e1a8b7@nvidia.com> Message-ID: Date: Tue, 7 Apr 2020 17:00:42 -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: <7895b9c6-f27d-8939-73d7-67d785e1a8b7@nvidia.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) 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=1586304032; bh=FSo44cZwUySuOimxsjMypd59TtiRcxs9yvJGq9wJ31U=; 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=eWO+inumv2c6wIMCFx9NG/PtbLJuwiteq8xjriDMNhpbO6r/tQK3XTUz71u9R+vsC Nj6NxYmpWlj3xzm+waTTG6jufCyNKXoGc/7AkPJsCzyPVfNJfydpdBOfxaC4TCu38Q ceEkIuC777ldHLwG2m/Sczo9EhnoyZrLAzK4+dr1IVc+AZ3b543Ijhfm1EvCBVyMik moOsZpCzqRTf3tZsqx7LWSm4dz84esu2nxvj0PAe+g+kktIP7k7GjMt7Ey5udZF9EP ckihbT8KTNIWzxEIeARv/u4sy5mYbwDbYBABEeK6mFVawHBY6GPZSWUftA/44B7NL8 rKqwB094rGP4A== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/7/20 4:59 PM, Sowjanya Komatineni wrote: > > On 4/7/20 4:38 PM, Sowjanya Komatineni wrote: >> >> 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=20 >>>>>>> HW and >>>>>>> also regarding capture threads where they use=20 >>>>>>> wait_event_interruptible >>>>>>> to prevent blocking waiting for buffers to be available for=20 >>>>>>> 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 chan= ge >>>>>> 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=20 >>>>> for >>>>> capture so as soon as VI HW issuing single shot is done and when=20 >>>>> 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=20 >>> buffer and between buffers obviously we have to wait for previous=20 >>> frames to finish and this why we have separate thread for frame=20 >>> finish where we can have next buffer capture ready and issue while=20 >>> previous frame memory write happens > Also we specified numbers buffers as 3 to vb2 queue. So this is rare=20 > case but to prevent issuing more than 2 at a time as VI HW is only=20 > double buffered and syncpt fifo max depth is 2 added this to be safer. To be more clear, when more buffers are enqueued from userspace always=20 capture list will be full and thread will be busy in capture till either=20 error or stop stream request happens.