From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: [PATCH] ALSA: hda - using POS_FIX_LPIB on Broadwell HDMI Audio Date: Thu, 08 May 2014 11:42:47 +0200 Message-ID: References: <1399485804-75028-1-git-send-email-libin.yang@intel.com> <96A12704CE18D347B625EE2D4A099D195232A6@SHSMSX103.ccr.corp.intel.com> <96A12704CE18D347B625EE2D4A099D19523313@SHSMSX103.ccr.corp.intel.com> <96A12704CE18D347B625EE2D4A099D1952333A@SHSMSX103.ccr.corp.intel.com> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by alsa0.perex.cz (Postfix) with ESMTP id D3A3C2610A8 for ; Thu, 8 May 2014 11:42:48 +0200 (CEST) In-Reply-To: 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 To: "Lin, Mengdong" Cc: "Yang, Libin" , "Li, Jocelyn" , "alsa-devel@alsa-project.org" , Pierre-Louis Bossart List-Id: alsa-devel@alsa-project.org At Thu, 8 May 2014 09:37:13 +0000, Lin, Mengdong wrote: > > Hi Takashi, > > Is it possible to accept this patch as a quick fix? Well, the question is whether this is specific to this board, or it's a generic issue of BDW HDMI controller. In the latter case, the fix is done in a wrong place. > It seems that a driver regression triggers this issue, since we don't have this problem two weeks ago. > We're still trying to locate the regression and checking the root cause. If it's a recent regression, I don't think it's good to apply a bandaid. There must be a cause (e.g. something changed in the graphics side) to fix properly. > This patch could avoid audio degradation atm before we have a better solution. The workaround can be applied easily via module option, and the machine isn't in the market yet. So I see no point to hurry too much for now... thanks, Takashi > Thanks > Mengdong > > > -----Original Message----- > > From: Takashi Iwai [mailto:tiwai@suse.de] > > Sent: Thursday, May 08, 2014 2:40 PM > > To: Yang, Libin > > Cc: alsa-devel@alsa-project.org; Lin, Mengdong; Pierre-Louis Bossart > > Subject: Re: [PATCH] ALSA: hda - using POS_FIX_LPIB on Broadwell HDMI Audio > > > > At Thu, 8 May 2014 06:28:17 +0000, > > Yang, Libin wrote: > > > > > > Hi Takashi, > > > > > > > -----Original Message----- > > > > From: Takashi Iwai [mailto:tiwai@suse.de] > > > > Sent: Thursday, May 8, 2014 2:20 PM > > > > To: Yang, Libin > > > > Cc: alsa-devel@alsa-project.org; Lin, Mengdong; Pierre-Louis Bossart > > > > Subject: Re: [PATCH] ALSA: hda - using POS_FIX_LPIB on Broadwell > > > > HDMI Audio > > > > > > > > At Thu, 8 May 2014 06:13:31 +0000, > > > > Yang, Libin wrote: > > > > > > > > > > Hi Takashi, > > > > > > > > > > > -----Original Message----- > > > > > > From: Takashi Iwai [mailto:tiwai@suse.de] > > > > > > Sent: Thursday, May 8, 2014 1:51 PM > > > > > > To: Yang, Libin > > > > > > Cc: alsa-devel@alsa-project.org; Lin, Mengdong; Pierre-Louis > > > > > > Bossart > > > > > > Subject: Re: [PATCH] ALSA: hda - using POS_FIX_LPIB on Broadwell > > > > > > HDMI Audio > > > > > > > > > > > > At Thu, 8 May 2014 05:48:04 +0000, Yang, Libin wrote: > > > > > > > > > > > > > > Hi Takashi, > > > > > > > > > > > > > > I checked the wallclock counter. The counter is OK. But it > > > > > > > failed to correct > > > > > > the position. > > > > > > > > > > > > So, how wrong the position buffer is? Is the problem intermittent? > > > > > > Please elaborate more. > > > > > > > > > > The issue is the position is almost always inaccurate. You will > > > > > hear there is > > > > intermittent noise in the sound. And the sound is played faster than > > > > it should be. > > > > > > > > > > The following message is what I got from dmesg: > > > > > > > > > > [ 73.278117] snd_hda_intel 0000:00:03.0: IRQ timing workaround is > > > > activated for card #0. Suggest a bigger bdl_pos_adj. > > > > > [ 73.528575] snd_hda_intel 0000:00:03.0: Unstable LPIB (26240 >= > > > > > 24064); disabling LPIB delay counting > > > > > > > > > > Do you think the print of wallclk and position information in the > > > > > function > > > > azx_position_ok() is useful to you? If yes, I will add debug code to > > > > print the info. > > > > > > > > It'd better to have the raw values of posbuf, lpib and wallclock for > > > > further analysis, yes. > > > > > > > > BTW, did you try non-snoop mode via snoop=0 option? > > > > > > I haven't tried non-snoop. Do I use `modprobe snd-hda-intel snoop=0` to use > > non-snoop mode? > > > > Yes. > > > > Takashi >