From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BC842CA9EB9 for ; Wed, 23 Oct 2019 20:56:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8CB9E20650 for ; Wed, 23 Oct 2019 20:56:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="xCTmUSic" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404100AbfJWU4A (ORCPT ); Wed, 23 Oct 2019 16:56:00 -0400 Received: from fllv0015.ext.ti.com ([198.47.19.141]:53920 "EHLO fllv0015.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390466AbfJWU4A (ORCPT ); Wed, 23 Oct 2019 16:56:00 -0400 Received: from lelv0265.itg.ti.com ([10.180.67.224]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id x9NKtZ2a094913; Wed, 23 Oct 2019 15:55:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1571864135; bh=MQTTyMjZXhjZnzwnc+GWMyroBk1W8/yLleURMf76qAk=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=xCTmUSicJiXP3Odt/mfxyUMmh2uaO4B0vwFE/Gwggx9WoCp9alSkasJIyoZ9PTGmT Xr1S5sxfZxX7wfPsEqwgv2D1mR7bWJo8m0gN3kv7+hjd+vmwVzHlB4dwXQlQ3hXUdk xZZesgXG6rJJI8ZbpDc6/2E+NXW98F0asgVpJxIg= Received: from DLEE115.ent.ti.com (dlee115.ent.ti.com [157.170.170.26]) by lelv0265.itg.ti.com (8.15.2/8.15.2) with ESMTPS id x9NKtZkL091790 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 23 Oct 2019 15:55:35 -0500 Received: from DLEE103.ent.ti.com (157.170.170.33) by DLEE115.ent.ti.com (157.170.170.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5; Wed, 23 Oct 2019 15:55:35 -0500 Received: from lelv0326.itg.ti.com (10.180.67.84) by DLEE103.ent.ti.com (157.170.170.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5 via Frontend Transport; Wed, 23 Oct 2019 15:55:25 -0500 Received: from [10.250.98.116] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0326.itg.ti.com (8.15.2/8.15.2) with ESMTP id x9NKtRTs077420; Wed, 23 Oct 2019 15:55:28 -0500 Subject: Re: [PATCH] dmaengine: cppi41: Fix cppi41_dma_prep_slave_sg() when idle To: Tony Lindgren , Peter Ujfalusi CC: Dan Williams , Vinod Koul , Alexandre Bailon , Andy Shevchenko , Bin Liu , Daniel Mack , Felipe Balbi , Johan Hovold , Sekhar Nori , Sebastian Andrzej Siewior , Sergei Shtylyov , , , , , Sebastian Reichel , Skvortsov , Yegor Yefremov References: <20191023153138.23442-1-tony@atomide.com> <245e1e8f-7933-bae1-b779-239f33d4d449@ti.com> <20191023171628.GO5610@atomide.com> <5deab8a9-5796-5367-213e-90c5961b8498@ti.com> <20191023191859.GQ5610@atomide.com> <7d578fe1-2d60-4a6e-48b0-73d66c39f783@ti.com> <20191023201829.GR5610@atomide.com> From: Grygorii Strashko Message-ID: Date: Wed, 23 Oct 2019 23:55:36 +0300 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: <20191023201829.GR5610@atomide.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On 23/10/2019 23:18, Tony Lindgren wrote: > * Peter Ujfalusi [191023 19:55]: >> On 10/23/19 10:18 PM, Tony Lindgren wrote: >>> We'd have to allow dma consumer driver call pm_runtime_get_sync() >>> on the dma device. Something similar maybe to what we have >>> for phy_pm_runtime_get_sync(). Or just get the device handle for >>> dma so the consumer can call pm_runtime_get_sync() on it. >> >> How much a pm_runtime_get_sync(dmadev) is different when it is issued by >> the client driver compared to when the dma driver issues it for it's own >> device? > > Well the consumer device could call pm_runtime_get_sync(dmadev) > when the USB cable is connected for example, and then call > pm_runtime_pu(dmadev) when let's say the USB cable is disconnected. > > Without using pm_runtime_irq_safe() we currently don't have a > clear path for doing this where the pm_runtime_get_sync(dmadev) > may sleep. > >> But I still fail to see the difference between the events before this >> patch and with the case when there is a 100ms delay between prep_sg and >> issue_pending. >> >> Before this patch: >> >> prep_sg() >> issue_pending() <- runtime_get() / put_autosuspend() >> _not_ starting transfer >> runtime_resume() <- starts the transfer >> >> With this patch and than 100ms delay between prep_sg and issue_pending: >> >> prep_sg() <- runtime_get() / put_autosuspend() >> runtime_resume() <- not starting transfer >> issue_pending() <- runtime_get() / put_autosuspend() >> starts the transfer >> >> With this patch, but more than 100ms delay in between: >> >> prep_sg() <- runtime_get() / put_autosuspend() >> runtime_resume() <- not starting transfer >>> 100ms delay >> runtime_suspend() >> issue_pending() <- runtime_get() / put_autosuspend() >> _not_ starting transfer >> runtime_resume() <- starts the transfer >> >> pm_runtime_get_sync() in issue_pending would be the solution to avoid >> delayed execution, but the usb driver should not assume that DMA is >> completed as soon as issue_pending returned. > > Oh I see. Yes the consumer driver would need to check for > the completed dma transfer in all cases. The delay issues > should not currently happen in the musb_ep_program() problem > case as it gets called from IRQ context. > > And no, adding pm_runtime_get_sync() to issue_pending is not > a solution. There may be clocks and regulators that need to > be powered up, and we don't want to use pm_runtime_irq_safe() > because of the permanent use count on the parent. 5 cents. I think the right thing might be to get rid of pm_runtime_xxx() in cppi41_dma_issue_pending(). So overall approach will be: - new job -> cppi41_dma_prep_slave_sg() -> pm_runtime_get() - issue_pending: fill backlog if suspended or run_queue if active (pm_runtime_active()) - job done: dmaengine_desc_get_callback_invoke() -> dmaengine_desc_get_callback_invoke(); pm_runtime_mark_last_busy(cdd->ddev.dev); pm_runtime_put_autosuspend(cdd->ddev.dev); in all places. It even might allow to get rid of cdd->lock. -- Best regards, grygorii