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<315241b5-f5a2-aaa0-7327-24055ff306c7@nvidia.com> <1b64a3c6-a8b9-34d7-96cc-95b93ca1a392@gmail.com> From: Jon Hunter Message-ID: <423eb28f-b5fc-c917-a7b2-72562183683f@nvidia.com> Date: Mon, 3 Feb 2020 11:37:44 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: quoted-printable DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1580729856; bh=ceXnFZ7jddmETXXwdfs4mGpj+O00W2KY/YQ322nXt4U=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=qXuwCM2rJ8br+WfWyobe/MOBDj1SnQ+sqtC2P5uvgpRUccqPpupsIKKpULWJuCtQy 6+QbNlZX687vt/qhOmx92gy1Pw3v7rccOBTqUiXn8aSGPyXtGngyhgs/b4F70poRYT HflYyjxCPZzn3obut9ctKGikXHbRtlIn2F/Gl9YHEdaZnc/fVJUbCCEc4t5ywtcCHT tjAk/8johzjzyOG9rnIKLdMoqAyLTOAN1mgi0zhYljIfFsCZRsZVUwTW++WsiNqgAH JiRUMU80FPLJEYHqhP2uynEgr2Gi/RKZazoeeDHl/eWOEztujVleq0XhrIEdFle+7g v+rjTZC4ZZUpQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/02/2020 15:13, Dmitry Osipenko wrote: > 31.01.2020 17:22, Dmitry Osipenko =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> 31.01.2020 12:02, Jon Hunter =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>> >>> On 30/01/2020 20:04, Dmitry Osipenko wrote: >>> >>> ... >>> >>>>>> The tegra_dma_stop() should put RPM anyways, which is missed in your= s >>>>>> sample. Please see handle_continuous_head_request(). >>>>> >>>>> Yes and that is deliberate. The cyclic transfers the transfers *shoul= d* >>>>> not stop until terminate_all is called. The tegra_dma_stop in >>>>> handle_continuous_head_request() is an error condition and so I am no= t >>>>> sure it is actually necessary to call pm_runtime_put() here. >>>> >>>> But then tegra_dma_stop() shouldn't unset the "busy" mark. >>> >>> True. >>> >>>>>> I'm also finding the explicit get/put a bit easier to follow in the >>>>>> code, don't you think so? >>>>> >>>>> I can see that, but I was thinking that in the case of cyclic transfe= rs, >>>>> it should only really be necessary to call the get/put at the beginni= ng >>>>> and end. So in my mind there should only be two exit points which are >>>>> the ISR handler for SG and terminate_all for SG and cyclic. >>>> >>>> Alright, I'll update this patch. >>> >>> Hmmm ... I am wondering if we should not mess with that and leave how >>> you have it. >> >> I took another look and seems my current v6 should be more correct becau= se: >> >> 1. If "busy" is unset in tegra_dma_stop(), then the RPM should be put >> there since tegra_dma_terminate_all() won't put RPM in this case: >> >> if (!tdc->busy) >> goto skip_dma_stop; >> >> 2. We can't move the "busy" unsetting into the terminate because then >> tegra_dma_stop() will be invoked twice. Although, one option could be to >> remove the tegra_dma_stop() from the error paths of >> handle_continuous_head_request(), but I'm not sure that this is correct >> to do. >=20 > Jon, I realized that my v6 variant is wrong too because > tegra_dma_terminate_all() -> tdc->isr_handler() will put RPM, and thus, > the RPM enable-count will be wrecked in this case. Did you see my other suggestion to move the pm_runtime_put() outside of tegra_dma_stop? There are only a few call sites for tegra_dma_stop and so if we call pm_runtime_put() after calling tegra_dma_stop this should simplify matters. Jon --=20 nvpublic