linux-kernel - Re: [alsa-devel][PATCH v4] ASoC: wm8960: Let wm8960 codec driver manage its own MCLK

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 29 Dec 2014 16:05:14 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Zidan Wang <B50113@...escale.com>
Cc:	"lgirdwood@...il.com" <lgirdwood@...il.com>,
	"perex@...ex.cz" <perex@...ex.cz>, "tiwai@...e.de" <tiwai@...e.de>,
	"lars@...afoo.de" <lars@...afoo.de>,
	"ckeepax@...nsource.wolfsonmicro.com" 
	<ckeepax@...nsource.wolfsonmicro.com>,
	"Li.Xiubo@...escale.com" <Li.Xiubo@...escale.com>,
	"patches@...nsource.wolfsonmicro.com" 
	<patches@...nsource.wolfsonmicro.com>,
	"alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [alsa-devel][PATCH v4] ASoC: wm8960: Let wm8960 codec driver
 manage its own MCLK

On Mon, Dec 29, 2014 at 10:59:08AM +0000, Zidan Wang wrote:
> Hi Mark,

Don't top post and please fix your mailer to word wrap within paragraphs
and avoid corrupting the mail it's quoting.

> You are right. When PM is disabled, the codec will not work. But there are also some codecs enable mclk in PM, such as wm8962, cs42xx8.
> And some codecs enable codec mclk in i2c probe(), startup() and set_bias_level(). It makes me confused.	
> Can you tell me what's the general idiom to enable mclk. Thanks.

Like I said in the mail to which you replied:

> > This isn't going to work if PM is disabled (which is still a valid configuration).  The general idiom for this is that the driver should start up with everything powered up then let runtime idle turn things off if they're not required.  That way if runtime PM is disabled then the system will still work as everything will just stay powered on all the time.

Download attachment "signature.asc" of type "application/pgp-signature" (474 bytes)