From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Nelson Subject: Re: [RFC PATCH 2/6] ASoC: sgtl5000: write all default registers Date: Fri, 06 Mar 2015 15:24:53 -0700 Message-ID: <54FA2935.6090701@boundarydevices.com> References: <1424991273-10081-1-git-send-email-eric.nelson@boundarydevices.com> <1424991273-10081-3-git-send-email-eric.nelson@boundarydevices.com> <20150306201406.GY21293@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by alsa0.perex.cz (Postfix) with ESMTP id AEA6726607D for ; Fri, 6 Mar 2015 23:24:58 +0100 (CET) Received: by pabrd3 with SMTP id rd3so30956666pab.5 for ; Fri, 06 Mar 2015 14:24:57 -0800 (PST) In-Reply-To: <20150306201406.GY21293@sirena.org.uk> 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: Mark Brown Cc: fabio.estevam@freescale.com, alsa-devel@alsa-project.org, lars@metafoo.de, tiwai@suse.de, lgirdwood@gmail.com, rmk+kernel@arm.linux.org.uk, jean-michel.hautbois@vodalys.com, troy.kisky@boundarydevices.com List-Id: alsa-devel@alsa-project.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi Mark, On 03/06/2015 01:14 PM, Mark Brown wrote: > On Thu, Feb 26, 2015 at 03:54:29PM -0700, Eric Nelson wrote: >> If an error occurs writing defaults, produce an error message >> but continue writing other registers. The failure of a single >> write should not cause catastrophic device failure. >> >> In at least one occurrence, I2C writes of CHIP_ANA_POWER was >> nacked, though continuing allowed the device to operate >> properly. > > I'm a bit nervous about this. Generally problems physically > writing to the device are pretty bad and lead to followon hard to > debug problems as the chip state drifts from the state the software > thinks it has. If this is a good idea I'd really like to see more > analysis as to why this is expected to happen and why it's OK. > I included this patch in the set because I found that the driver would fail through a soft re-boot until I found the dependencies of CHIP_CLK_CTRL and LINREG_CTRL in setting the initial value for ANA_POWER. By ignoring the failed register write, I found that I had functioning audio. Which begs the question: should we force complete failure on what may be an intermittent problem. My preference is no. This is really un-related to the rest of the patch set. Regards, Eric -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJU+ik1AAoJEFUqXmm9AiVrRxYIAKvfJooQbhFu0um3bcX2e4sj 0AcBhn8P1brHv9gGkq68iEpQUA7E4nzSeOlmjlE6wLiC2tzHPdRsUFfHpAtrIMk5 CSdw3Qs9ti7jZkj0bRPVo0yINO7PxtCujvClfXETPNuyn78xy9lFK5PTX1sjZEso Apeiz7smduItcFfBAGlcARK29b86cqJApKGNkzLL6J+NpmQptvrl3ijgohEPMB1/ 4ubyt4K/0dCGON1UqFyMr5LKAlTjG2ctMM+10O7b2JpULwQqUpXSrobvT1syPSKZ haa16ir8AYD5IWYMsUy/vWKDTrN2Vj+7pYdrpnW3ermVyqnSY7B0jx73REnjbbY= =gk5O -----END PGP SIGNATURE-----