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[209.132.180.67]) by mx.google.com with ESMTP id i78si91036oib.1.2020.01.07.07.15.10; Tue, 07 Jan 2020 07:15:23 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=LWgsm1OR; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728384AbgAGPOA (ORCPT + 99 others); Tue, 7 Jan 2020 10:14:00 -0500 Received: from hqnvemgate25.nvidia.com ([216.228.121.64]:17777 "EHLO hqnvemgate25.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728372AbgAGPN6 (ORCPT ); Tue, 7 Jan 2020 10:13:58 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate25.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 07 Jan 2020 07:13:40 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Tue, 07 Jan 2020 07:13:57 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Tue, 07 Jan 2020 07:13:57 -0800 Received: from [10.26.11.139] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 7 Jan 2020 15:13:55 +0000 Subject: Re: [PATCH v3 09/13] dmaengine: tegra-apb: Remove runtime PM usage To: Dmitry Osipenko , Laxman Dewangan , Vinod Koul , Dan Williams , Thierry Reding , =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= CC: , , References: <20200106011708.7463-1-digetx@gmail.com> <20200106011708.7463-10-digetx@gmail.com> From: Jon Hunter Message-ID: Date: Tue, 7 Jan 2020 15:13:52 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200106011708.7463-10-digetx@gmail.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL101.nvidia.com (172.20.187.10) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1578410020; bh=Sf0ckx5pEctxgD10OMRT1lnch6V57nc9NpAJxMakDd4=; 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=LWgsm1ORkmkJ0tg8Uqw2z2plcb298KilPFwVAdMJeRU69ugZwZh+ImPailCMGibXS JUK6rBM79/VREU15uTjOVxQZM1NZrJOX/I1psObzTqmy9tI3Ooq7GQVRxT2/sBk+Aj 7xRZ+D9i1SJ1FHRQeu/RqGbkN1rWuBcAD58EEk9WarnNwNhd658HB7szBeQthZliKn 1WumM0vQyo0UrNOxIVwBT70Zr4KgxsfRYy9n3j4Umw8cCwaWWQvs8vGdiAmGPwoDEd GO4a/jaCc0PgYHNj6j3Po+DybaZZDMPTXwFhnOo41QYQP1I04o7nrJokUaV3RnAg4J IrBEPFvyh1P4w== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/01/2020 01:17, Dmitry Osipenko wrote: > There is no benefit from runtime PM usage for the APB DMA driver because > it enables clock at the time of channel's allocation and thus clock stays > enabled all the time in practice, secondly there is benefit from manually > disabled clock because hardware auto-gates it during idle by itself. This assumes that the channel is allocated during a driver initialisation. That may not always be the case. I believe audio is one case where channels are requested at the start of audio playback. Jon -- nvpublic