From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [PATCH 1/2] i2c: designware: device tree bindings for i2c speed mode Date: Wed, 20 Aug 2014 10:36:21 +0100 Message-ID: <20140820093621.GC21174@leverpostej> References: <1408473276-10847-1-git-send-email-atull@opensource.altera.com> <20140820093459.GB21174@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20140820093459.GB21174@leverpostej> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "atull-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org" Cc: "wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org" , "baruch-NswTu9S1W3P6gbPvEgmw2w@public.gmane.org" , "mika.westerberg-VuQAYsv1563Yd54FQh9/CA@public.gmane.org" , "grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "skuribay-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org" , "Romain.Baeriswyl-ux6zf3SgZrrQT0dZR+AlfA@public.gmane.org" , "rafael.j.wysocki-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org" , "alan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org" , "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "delicious.quinoa-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , "dinguyen-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org" , "yvanderv-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org" List-Id: devicetree@vger.kernel.org On Wed, Aug 20, 2014 at 10:34:59AM +0100, Mark Rutland wrote: > On Tue, Aug 19, 2014 at 07:34:35PM +0100, atull-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org wrote: > > From: Alan Tull > > > > Add "speed-mode" Device Tree property to select between > > standard and fast i2c mode. Previously, driver was hardwired > > as fast mode. Default to fast mode if property is not > > present. > > > > Signed-off-by: Alan Tull > > --- > > .../devicetree/bindings/i2c/i2c-designware.txt | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt > > index 5199b0c..0e4cd21 100644 > > --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt > > +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt > > @@ -9,6 +9,8 @@ Required properties : > > Recommended properties : > > > > - clock-frequency : desired I2C bus clock frequency in Hz. > > + - speed-mode : 0 = standard (0 - 100Kb/s) > > + : 1 = fast (<= 400Kb/s) <== default > > This is a bit opaque. > > Is this a limit on the max bit-rate the device should operate at? > > Why not just have an optional boolean property to limit to standard > speed? I see there's a new patch doing this based on clock-frequency, so feel free to ignore this. Mark.