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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 20F35C433DF for ; Fri, 15 May 2020 07:21:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ED7662065F for ; Fri, 15 May 2020 07:21:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726645AbgEOHVN (ORCPT ); Fri, 15 May 2020 03:21:13 -0400 Received: from mx2.suse.de ([195.135.220.15]:49682 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726496AbgEOHVM (ORCPT ); Fri, 15 May 2020 03:21:12 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 3553AACC5; Fri, 15 May 2020 07:21:14 +0000 (UTC) Date: Fri, 15 May 2020 09:21:10 +0200 Message-ID: From: Takashi Iwai To: Brent Lu Cc: , Jaroslav Kysela , Takashi Iwai , Baolin Wang , Arnd Bergmann , Greg Kroah-Hartman , Richard Fontana , Thomas Gleixner , paulhsia , Subject: Re: [PATCH] ALSA: pcm: fix incorrect hw_base increase In-Reply-To: <1589515779-20987-1-git-send-email-brent.lu@intel.com> References: <1589515779-20987-1-git-send-email-brent.lu@intel.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") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 15 May 2020 06:09:39 +0200, Brent Lu wrote: > > The hw_base will be increased by runtime->buffer_size frames > unconditionally if the runtime->status->hw_ptr is not updated for over > half of buffer time. As the hw_base increases, so does the > runtime->status->hw_ptr which could lead to invalid return value when > user space program calls snd_pcm_avail() function. > > By updating runtime->hw_ptr_jiffies each time the HWSYNC is called, > the hw_base will keep the same when buffer stall happens, so does the > hw_ptr. Updating hw_ptr_jiffies at that code path looks correct, but it still leaves the question why this condition happens. It means that the actual hwptr isn't changed and yet only jiffies increase significantly; it means that the hardware can't report proper pointer, and it should have set SNDRV_PCM_INFO_BATCH flag, then the jiffies check is skipped. With which hardware and under which situation did it happen (and the patch fixed)? thanks, Takashi > > Signed-off-by: Brent Lu > --- > sound/core/pcm_lib.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c > index 872a852..d531e1b 100644 > --- a/sound/core/pcm_lib.c > +++ b/sound/core/pcm_lib.c > @@ -433,6 +433,7 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, > > no_delta_check: > if (runtime->status->hw_ptr == new_hw_ptr) { > + runtime->hw_ptr_jiffies = curr_jiffies; > update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp); > return 0; > } > -- > 2.7.4 >