From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christophe Aeschlimann Subject: Re: ALSA issue on DA850/OMAP-L138/AM18x Date: Mon, 21 Mar 2011 13:15:37 +0100 Message-ID: <4D874169.9010202@acn-group.ch> References: <4D5BDA3D.5080905@acn-group.ch> <4D749A09.8050101@acn-group.ch> <4D762FEB.3010003@acn-group.ch> <4D870A59.9050004@acn-group.ch> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: davinci-linux-open-source-bounces-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org Errors-To: davinci-linux-open-source-bounces-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org To: "Bedia, Vaibhav" Cc: "khilman-1D3HCaltpLuhEniVeURVKkEOCMrvLtNR@public.gmane.org" , "alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org" , "davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: alsa-devel@alsa-project.org On 21.03.2011 12:24, Bedia, Vaibhav wrote: > On Monday, March 21, 2011 1:51 PM, Christophe Aeschlimann wrote: > [...] >> In this end it was a HW issue. >> >> Problem solved. >> > = > If you don't mind, can you please elaborate on what the h/w issue was and= how you fixed it? > = > Regards, > Vaibhav The symptoms were slightly different on our custom board which uses a TLV320AIC3107 codec : After every cold boot the system would take ~7 seconds to start recording. Recording a second time just after the first time would behave normally (without delay). This delay was because the ADC (audio input) starts working when the volts reach 1.35V (common mode) on the ADC. But a 10uF series capacitor was delaying the ramp-up by 7 seconds. Reducing the capacitor size changed the delay to something more reasonable (ms range). This "issue" is described in the TLV320AIC3107 codec under "INPUT IMPEDANCE AND VCM CONTROL" the 2nd paragraph. (they also offer a workaround but this was not of a practical use in our case). Hope this helps. Regards, -- = Christophe Aeschlimann Embedded Software Engineer & IT Manager ACN Advanced Communications Networks S.A. Rue du Puits-Godet 8a 2000 Neuch=E2tel, Switzerland T=E9l. +41 32 724 74 31 c.aeschlimann-5/WUhD8XThOVQ4qyx6sgCw@public.gmane.org