linux-kernel - Re: [PATCH] ASoC: wm_hubs: Fix DC Servo readback

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]

Message-ID: <20140813113841.GP17528@sirena.org.uk>
Date:	Wed, 13 Aug 2014 12:38:41 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
Cc:	Nikesh Oswal <nikesh@...nsource.wolfsonmicro.com>,
	lgirdwood@...il.com, tiwai@...e.de, alsa-devel@...a-project.org,
	patches@...nsource.wolfsonmicro.com, linux-kernel@...r.kernel.org,
	perex@...ex.cz
Subject: Re: [PATCH] ASoC: wm_hubs: Fix DC Servo readback

On Wed, Aug 13, 2014 at 12:08:44PM +0100, Charles Keepax wrote:
> On Wed, Aug 13, 2014 at 11:47:20AM +0100, Nikesh Oswal wrote:

> >  	case 2:
> >  		dcs_reg = WM8994_DC_SERVO_4E;
> >  		break;
> > -	case 1:
> > -		dcs_reg = WM8994_DC_SERVO_READBACK;
> > -		break;
> >  	default:
> >  		dcs_reg = WM8993_DC_SERVO_3;
> >  		break;

> This doesn't look right, firstly if it is the same register for
> all versions then surely we should change the code that sets
> dcs_readback_mode rather than setting that to different values
> but treating them the same. Although obviously if nothing still
> uses this case we could remove it as well.

> Also I think the situation is more complex for example on version
> 4.4 of the datasheet for wm8994 the WR_VAL fields appear to be in
> register 59h. Which is not consistent with this.

There was a change in the DC servo between revisions of the WM8994 (at
revision E from the look of the code).  This isn't documented in the
datasheets as they only document current silicon.

Download attachment "signature.asc" of type "application/pgp-signature" (820 bytes)