From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: Set eapd to follow stream on or off Date: Tue, 20 May 2014 11:35:19 +0200 Message-ID: References: <3143A3763CC94AB9AAD48E43EA2B4DFC@realtek.com.tw> <72897913D05F4C12BCED9FF890C77D61@realtek.com.tw> <66A4EBB5FA74484E9FB040780F3C8965@realtek.com.tw> 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 7B2B1265007 for ; Tue, 20 May 2014 11:35:20 +0200 (CEST) In-Reply-To: <66A4EBB5FA74484E9FB040780F3C8965@realtek.com.tw> 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: Kailang Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org At Tue, 20 May 2014 17:20:44 +0800, Kailang wrote: > > > > At Tue, 20 May 2014 16:52:43 +0800, > > Kailang wrote: > >> > >> > >> > At Tue, 20 May 2014 15:15:49 +0800, > >> > Kailang wrote: > >> >> > >> >> Hi Takashi, > >> >> > >> >> HP machine had pop noise via speaker. > >> >> If EAPD on or off, speaker will have pop noise. > >> >> So, they want to set eapd to follow with stream on or off. > >> > > >> > I can apply this as is, but still I wonder whether this results in > >> > other problems. Doing EAPD on/off there means that it happens far > >> > more often. For example, what happens if you do like below? > >> > > >> > while true; do > >> > echo -n > /dev/snd/pcmC0D0p > >> > done > >> > > >> > And, what if the device is resumed from power-saving by an audio > >> > playback? Immediately after the power up, it'll start the streaming, > >> > so it'll turn on EAPD. > >> > > >> > That said, isn't it just a need for some delay before EAPD on/off? > >> > >> No, eapd on or off will cause pop noise. > > > > Does it do always? > No, pop noise just one pop sound. It can not remove by software. > But this machine need to do this always. So, doing EAPD on/off often is rather worse. It's what your patch does. Once again: did you try the script above? If the pop noise always happens, the operation like above is the worst scenario. Then, let's think again how to *reduce* it. We need one EAPD on at least after each power up. But it's needed only when you actually plays a stream. That is, we need only enable EAPD at playback stream open, but leave EAPD as is at close. Takashi > >> Our customer just want to do eapd on when stream is open. > >> The pop noise will not clear. Because music gain was biger than pop > >> noise. > > > > Opening a stream doesn't mean that it follows the loud sound > > immediately. The script above wouldn't produce any sound but just > > does open/close the stream. Did you try that? > > > > > > Takashi > > > > ------Please consider the environment before printing this e-mail. >