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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 0B7C7C43381 for ; Tue, 2 Mar 2021 08:41:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2EFE64DE4 for ; Tue, 2 Mar 2021 08:41:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1837672AbhCBId3 (ORCPT ); Tue, 2 Mar 2021 03:33:29 -0500 Received: from mx1.opensynergy.com ([217.66.60.4]:20997 "EHLO mx1.opensynergy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377386AbhCBISz (ORCPT ); Tue, 2 Mar 2021 03:18:55 -0500 Received: from SR-MAILGATE-02.opensynergy.com (localhost.localdomain [127.0.0.1]) by mx1.opensynergy.com (Proxmox) with ESMTP id 3AF25A1377; Tue, 2 Mar 2021 09:09:34 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=opensynergy.com; h=cc:cc:content-transfer-encoding:content-type:content-type :date:from:from:in-reply-to:message-id:mime-version:references :reply-to:subject:subject:to:to; s=srmailgate02; bh=P6/66ow1A9Ra Gw2rLTTCJZFYqqpmdHnFdrJWuGPR8cg=; b=TEL012p3TgzQcjhpPXrfiT2EIDQE VjQMCmQRC5+rK3lWClcyRIro2Ne5V6DYW26g+b8WTPBiCZXSvHDKpKZ4lzygy0CY P1P6AbfitmPTFAXiPufkFLsl47OOYOv4HRBLU3pAmleHzfDF0OQR5q3qRVy7CcA7 ezVxxO5mBT8nLez/0qJei0pnXtMca9mlQkk+AJf30pSDR8QY+T5vYD7pYyTFiDLV oWRjdKE5TRrBy9Aq2kNWr55wrP7j1ZEUIPf1s/iZkuyjyp8ppYpAfAaveoxOvpt2 llx2nSFzYTHP5EJnz6cCD1x/a9z//XOjqiU5DMq0CdAkl5B00vpyzARflA== Subject: Re: [PATCH v6 9/9] ALSA: virtio: introduce device suspend/resume support To: Takashi Iwai CC: , , , "Michael S. Tsirkin" , Jaroslav Kysela , Takashi Iwai , References: <20210227085956.1700687-1-anton.yakovlev@opensynergy.com> <20210227085956.1700687-10-anton.yakovlev@opensynergy.com> <7d4daea0-ed59-e84c-c28a-945c49204c83@opensynergy.com> From: Anton Yakovlev Message-ID: Date: Tue, 2 Mar 2021 09:09:33 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SR-MAIL-02.open-synergy.com (10.26.10.22) To SR-MAIL-01.open-synergy.com (10.26.10.21) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02.03.2021 07:48, Takashi Iwai wrote: > On Tue, 02 Mar 2021 07:29:20 +0100, > Anton Yakovlev wrote: >> >> On 28.02.2021 13:05, Takashi Iwai wrote: >>> On Sat, 27 Feb 2021 09:59:56 +0100, >>> Anton Yakovlev wrote: >>>> >> >> [snip] >> >>>> --- a/sound/virtio/virtio_pcm.c >>>> +++ b/sound/virtio/virtio_pcm.c >>>> @@ -109,6 +109,7 @@ static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *vss, >>>> SNDRV_PCM_INFO_BATCH | >>>> SNDRV_PCM_INFO_BLOCK_TRANSFER | >>>> SNDRV_PCM_INFO_INTERLEAVED | >>>> + SNDRV_PCM_INFO_RESUME | >>>> SNDRV_PCM_INFO_PAUSE; >>> >>> Actually you don't need to set SNDRV_PCM_INFO_RESUME. >>> This flag means that the driver supports the full resume procedure, >>> which isn't often the case; with this, the driver is supposed to >>> resume the stream exactly from the suspended position. >>> >>> Most drivers don't set this but implement only the suspend-stop >>> action. Then the application (or the sound backend) will re-setup the >>> stream and restart accordingly. >> >> I tried to resume driver without SNDRV_PCM_INFO_RESUME, and alsa-lib >> called only ops->prepare(). It makes sense for a typical hw, but we have >> "clean" unconfigured device on resume. And we must set hw parameters as >> a first step. It means, that code should be more or less the same. And >> maybe it's better to set SNDRV_PCM_INFO_RESUME, since it allows us to >> resume substream in any situation (regardless of application behavior). >> I can refactor code to only send requests from trigger(RESUME) path and >> not to call ops itself. It should make code more straitforward. What do >> you say? > > How about calling hw_params(NULL) conditionally in the prepare? Then the question is that condition. When ops->prepare() is called, the substream is in SUSPENDED state or not? If not then we need to track this in some additional field (and it will make logic a little bit clumsy, since that field is needed to be carefully handled in other places). > Doing the full stack work in the trigger callback is bad from the API > design POV; in general the trigger callback is supposed to be as short > as possible. Yeah, but usually original subsystem design does not take into account para-virtualized devices, which usually have it's own slightly different reality. And we need to introduce some tricks. > > Takashi > -- Anton Yakovlev Senior Software Engineer OpenSynergy GmbH Rotherstr. 20, 10245 Berlin