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: Wed, 8 Dec 2010 04:01:46 +0000 Message-ID: <20101208040146.GP20097@trinity.fluff.org> References: <20101207110705.69792a1a@endymion.delvare> <20101207115325.GN20097@trinity.fluff.org> <20101207160739.0d7141f3@endymion.delvare> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20101207160739.0d7141f3-R0o5gVi9kd7kN2dkZ6Wm7A@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jean Delvare Cc: Ben Dooks , Linux I2C List-Id: linux-i2c@vger.kernel.org On Tue, Dec 07, 2010 at 04:07:39PM +0100, Jean Delvare wrote: > Hi Ben, > > On Tue, 7 Dec 2010 11:53:25 +0000, Ben Dooks 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. > > > + if (bit_adap->getscl == NULL) { > > > + dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n"); > > > > I'll have a think about wording. I might be able to improve it. > > > > As a note, I always prefer cannot to can't. > > And I thought you were a busy developer ;) I've my reasons for this, blame my parents. > There is no trend one way or another, neither in the kernel tree nor > even in drivers/i2c specifically. no, just my preference. > > > + dev_warn(&adap->dev, "Bus may be unreliable\n"); > > > > if there are any other warnings, should we print just one unreliable warning > > at the end of the scan? > > I'm not sure what "scan" you refer to, and in all honesty I'm not sure > I get your point at all. ok, looking at the code it isn't important. -- Ben Q: What's a light-year? A: One-third less calories than a regular year.