Hi Michael, On Fri, 11 Jun 2010 08:31:59 +0200, Michael Lawnick wrote: > Jean Delvare said the following: > > Hi Michael, > > > >> + list_add_tail(&priv->adap.mux_list, &parent->mux_list_head); > > > > The driver core maintains a device tree already, do you really need to > > keep your own? We've tried hard to remove all redundancy between > > i2c-core and the driver core in the last couple years, so I really would > > like us to not add such redundancy back now. > > > > If you have a good reason to have your own list, please explain. If > > not, please get rid of it. > > > this is a core part of mux management. You need it for checking whether > the current client that is to be added is already present. > The problem is to efficiently parse down a mux tree towards the leaves. > Sub-muxes are registered as i2c clients to their upper bus. This is correct, but irrelevant, as far as I can see. When walking an I2C segment tree towards the leaves, you care about the segments themselves (struct i2c_adapter), not the mux chips. In your architecture, muxed segments are direct children of the root segment from the device tree perspective, not children of the mux chip. > I found no way to separate muxes from normal clients. If you have to, it is easy, the driver core has support for this already. Search for i2c_client_type and i2c_adapter_type in i2c-core.c. We could add i2c_mux_type easily. But as I wrote above, I don't think we need this. > So there were two ideas: > invent a client-type field in i2c-client or to hold a separate list. > The first one e.g. would have the possibility to provide basic info in sysFs > but I feared a general debate. So I decided to go the other way which is > hidden to the outer world. > > If you don't like this way, I'd need some ideas how to do it. I would walk the device tree maintained by the driver core (using device_for_each_child) and filtering out irrelevant devices. Basically filtering on dev->type == &i2c_adapter_type should do the trick, methinks. Is there anything I am missing? Thanks, -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
