From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: question : crash between kernel i2c and alsa i2c Date: Tue, 14 Jun 2005 10:35:29 +0200 Message-ID: References: <42AD5670.6070900@avantwave.com> <42AE3411.9040709@avantwave.com> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Return-path: Received: from mx2.suse.de (ns2.suse.de [195.135.220.15]) by alsa.jcu.cz (ALSA's E-mail Delivery System) with ESMTP id D348016E for ; Tue, 14 Jun 2005 10:35:34 +0200 (MEST) In-Reply-To: <42AE3411.9040709@avantwave.com> Sender: alsa-devel-admin@lists.sourceforge.net Errors-To: alsa-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Tomko Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org At Tue, 14 Jun 2005 09:34:09 +0800, Tomko wrote: > > Takashi Iwai wrote: > > >At Mon, 13 Jun 2005 17:48:32 +0800, > >Tomko wrote: > > > > > >>Hi everyone, > >> > >>I know that there is a tiny i2c subsystem inside alsa , i would like to > >>know is there any control betwen the kernel i2c subsystem and the alsa > >>i2c ? Will there any crashes if two i2c access the bus togethre ? > >> > >> > > > >No, they have no relevence between them at all. > >If you try to access the same hardware, of course it would be a > >problem. But ALSA's i2c usually accesses only the chip-connection in > >the sound card, which is quite unlikely accessed from kernel i2c. > > > > > > > No, what i mean is what if they are accessing different device ? for > example kernel access it's own i2c device but alsa access it's i2c audio > device , but there is only ONE pair of i2c bus in hardware, just like > when the alsa's i2c just initiate a "START" and throw out the hardware > address but kernel's i2c want to initiate a "START" also and throw out > another hardware address . How's this situation be avoided if there is > no control between two i2c subsystem? In such a case, use kernel i2c layer for all controls. As mentioned above, ALSA i2c was introduced mainly as a very simple i2c control _on the sound card_, which the kernel i2c drivers don't cover. If you have a kernel i2c driver, you should use it. Takashi ------------------------------------------------------- This SF.Net email is sponsored by: NEC IT Guy Games. How far can you shotput a projector? How fast can you ride your desk chair down the office luge track? If you want to score the big prize, get to know the little guy. Play to win an NEC 61" plasma display: http://www.necitguy.com/?r=20