From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Dooks Subject: Re: [PATCH 2/2] i2c-algo-bit: Complain about masters which can't read SCL Date: Tue, 7 Dec 2010 12:30:11 +0000 Message-ID: <20101207123011.GO20097@trinity.fluff.org> References: <20101207110705.69792a1a@endymion.delvare> <20101207121009.GD10722@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20101207121009.GD10722-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Brown Cc: Jean Delvare , Linux I2C List-Id: linux-i2c@vger.kernel.org On Tue, Dec 07, 2010 at 12:10:10PM +0000, Mark Brown wrote: > On Tue, Dec 07, 2010 at 11:07:05AM +0100, Jean Delvare wrote: > > The I2C specification explicitly describes both SDA and SCL as > > bidirectional lines. An I2C master with a read-only SCL is thus not > > compliant. If a slow slave stretches the clock, errors will happen, > > so the bus can't be considered as reliable. > > > > Signed-off-by: Jean Delvare > > It'd be good to also flag this via sysfs so that it's more readily > visible to things like diagnostic tools. Could be, I wonder how many other hardware based adapters just don't do this. Quite a few devices i've seen don't use it as they're generally fast enough, or implement some other status polling system. -- Ben Q: What's a light-year? A: One-third less calories than a regular year.