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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 397A1C433ED for ; Fri, 30 Apr 2021 12:00:05 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BBE4561419 for ; Fri, 30 Apr 2021 12:00:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BBE4561419 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:49458 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lcRoR-0000HF-Dv for qemu-devel@archiver.kernel.org; Fri, 30 Apr 2021 08:00:03 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37710) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lcQpR-0000hF-0J for qemu-devel@nongnu.org; Fri, 30 Apr 2021 06:57:01 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:29700) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lcQpP-0004s0-9B for qemu-devel@nongnu.org; Fri, 30 Apr 2021 06:57:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619780218; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=hbhCUiDwVWC6nGjLVYOP+rkOerjYQNS1kEYi7+OI09A=; b=KJn9CL4uYcmMh/BQusYk8nHPlsx/f9DXjMKPAr+hXma1nL/ApUoRi/9mB9F4gcA+Ug3Hxa TqGgipSN2DUK6ztPHErFy7jJHgg6Z8meZD86gK12Zbp9fBx1ZXQRnnnDA8DhRJi/e9mBj0 FA4gIG0dEwwxlBt4klnz6SPLD9zVSFU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-341-zByWYXPpNaK9zz0wPK79mg-1; Fri, 30 Apr 2021 06:56:57 -0400 X-MC-Unique: zByWYXPpNaK9zz0wPK79mg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D302818B9ECC; Fri, 30 Apr 2021 10:56:55 +0000 (UTC) Received: from sirius.home.kraxel.org (ovpn-112-203.ams2.redhat.com [10.36.112.203]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 53F715F707; Fri, 30 Apr 2021 10:56:52 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id B0B051800380; Fri, 30 Apr 2021 12:56:50 +0200 (CEST) Date: Fri, 30 Apr 2021 12:56:50 +0200 From: Gerd Hoffmann To: Shreyansh Chouhan Subject: Re: [RFC PATCH 00/27] Virtio sound card implementation Message-ID: <20210430105650.k67lebhrtofm5vz2@sirius.home.kraxel.org> References: <20210429120445.694420-1-chouhan.shreyansh2702@gmail.com> MIME-Version: 1.0 In-Reply-To: <20210429120445.694420-1-chouhan.shreyansh2702@gmail.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kraxel@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=kraxel@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.22, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, mst@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi, > - The output from the sound card is accompanied by periodic > white noise. I do not know why this is happening. I tried > debugging it by writing the buffers to a new wav file and > sure enough the contents of the file were different at > some places, but I couldn't find what must be causing it. > (Relevant patches: #19, #20, #21 and #25.) What steps should > I take for debugging this? Hmm, I'd try to simplify the code. The two helper functions virtio_snd_pcm_get_buf() + virtio_snd_pcm_handle_buf_written() look rather complex to me. I'd suggest to make them handle a single virtqueue element only. That should make the logic simpler. The loop in virtio_snd_output_cb() will need to take a few more rounds then, and virtio_snd_pcm_get_buf() would probably have to return the number of bytes it actually placed in the buffer so you can pass on that value to AUD_write(). For actual debugging I typically use trace points or temporary debug printfs or a combination of both. I'd suggest logging the buffer handling, filling them from virt queue, writing to AUD, also log the offset, maybe something goes wrong with partial writes. > - What is the suggested way of waiting? When the driver issues > the VIRTIO_SND_PCM_STOP ctrl command I want to wait for the > buffers existing in tx vq to be consumed before closing the > stream. Store a pointer to the virtqueue element, then complete it when virtio_snd_output_cb() processed all pending buffers. take care, Gerd