From patchwork Thu Mar 22 14:28:35 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Takashi Iwai X-Patchwork-Id: 10301607 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 739D260385 for ; Thu, 22 Mar 2018 14:28:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5E2042223E for ; Thu, 22 Mar 2018 14:28:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 50F8222376; Thu, 22 Mar 2018 14:28:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1C7E126E51 for ; Thu, 22 Mar 2018 14:28:43 +0000 (UTC) Received: from alsa0.perex.cz (localhost [127.0.0.1]) by alsa0.perex.cz (Postfix) with ESMTP id 80E0E26739E; Thu, 22 Mar 2018 15:28:41 +0100 (CET) X-Original-To: alsa-devel@alsa-project.org Delivered-To: alsa-devel@alsa-project.org Received: by alsa0.perex.cz (Postfix, from userid 1000) id D6E5926739F; Thu, 22 Mar 2018 15:28:38 +0100 (CET) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by alsa0.perex.cz (Postfix) with ESMTP id 9E8D826739D for ; Thu, 22 Mar 2018 15:28:36 +0100 (CET) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id C8276AF68; Thu, 22 Mar 2018 14:28:35 +0000 (UTC) Date: Thu, 22 Mar 2018 15:28:35 +0100 Message-ID: From: Takashi Iwai To: In-Reply-To: <1521726537-7651-1-git-send-email-twischer@de.adit-jv.com> References: <1521726537-7651-1-git-send-email-twischer@de.adit-jv.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Cc: alsa-devel@alsa-project.org Subject: Re: [alsa-devel] [PATCH - IOPLUG DRAIN 0/2] X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org X-Virus-Scanned: ClamAV using ClamSMTP On Thu, 22 Mar 2018 14:48:55 +0100, wrote: > > > Hi Takashi, > > > Why not poll()? > > > IOW, why ioplug must be handled specially regarding the non-blocking > >operation? The normal kernel driver behaves like that (returning > > -EAGAIN, and let apps to sync with poll()). > > > What do you think about the following solution? > > (I thought the whole time that you have to use snd_pcm_wait() to wait for drain > in nonblocking mode but you have to use the poll_descriptors directly.) > > Know I am expecting that the user is calling poll() > if snd_pcm_drain() returns -EAGAIN and > the user has to call snd_pcm_drain() again after poll returns > to check if drain is done. Well, the drain callback *should* block and wait until drained. That was the intention of the callback. What I suggested instead is that ioctl shouldn't call drain callback in non-blocking mode, but it should return -EAGAIN there. That said, a change like below. And in the plugin side, it can assume the blocking mode and simply waits until drained. thanks, Takashi diff --git a/src/pcm/pcm_ioplug.c b/src/pcm/pcm_ioplug.c index 8c0ed4836365..33f7c5c27b6f 100644 --- a/src/pcm/pcm_ioplug.c +++ b/src/pcm/pcm_ioplug.c @@ -494,12 +494,37 @@ static int snd_pcm_ioplug_drain(snd_pcm_t *pcm) ioplug_priv_t *io = pcm->private_data; int err; - if (io->data->state == SND_PCM_STATE_OPEN) + switch (io->data->state) { + case SND_PCM_STATE_OPEN: + case SND_PCM_STATE_DISCONNECTED: + case SND_PCM_STATE_SUSPENDED: return -EBADFD; + case SND_PCM_STATE_PREPARED: + if (pcm->stream == SND_PCM_STREAM_PLAYBACK) { + snd_pcm_lock(pcm); + err = snd_pcm_ioplug_start(pcm); + snd_pcm_unlock(pcm); + if (err < 0) + return err; + io->data->state = SND_PCM_STATE_DRAINING; + } + break; + case SND_PCM_STATE_RUNNING: + io->data->state = SND_PCM_STATE_DRAINING; + break; + } + + if (io->data->state == SND_PCM_STATE_DRAINING) { + if (io->data->nonblock) + return -EAGAIN; + + if (io->data->callback->drain) { + err = io->data->callback->drain(io->data); + if (err < 0) + return err; + } + } - io->data->state = SND_PCM_STATE_DRAINING; - if (io->data->callback->drain) - io->data->callback->drain(io->data); snd_pcm_lock(pcm); err = snd_pcm_ioplug_drop(pcm); snd_pcm_unlock(pcm);