Hi, On Sat, Dec 15, 2012 at 11:21:36PM +0900, Mark Brown wrote: > On Fri, Dec 14, 2012 at 09:06:49AM -0700, Stephen Warren wrote: > > On 12/13/2012 10:50 PM, Naveen Krishna Chatradhi wrote: > > > > +The first should be an output, and is used to claim the I2C bus, > > > +the second should be an input, and signals that the other side (Client) > > > +wants to claim the bus. This allows two masters to share the same I2C bus. > > > I'm confused why this is even needed; the I2C protocol itself defines > > how multi-master is supposed to work, just using the regular SCL/SDA lines. > > Practically speaking essentially no systems actually do that - mostly > Linux will treat failure to get the bus as an error for example. It is true that Linux currently does not have proper multi-master support. It is worth a look what is missing and how far we can get with the I2C specified arbitration IMO. > also get things like read operations which appear as multiple > transactions on the I2C bus so require something higher level than what > multi-master provides. I don't get what you mean here. Can you elaborate? That being said. Grant's design was the most promising one. Thanks, Wolfram -- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ |
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