Hi, On 24.09.2004 20:05, Jean Delvare wrote: >>We like to have an completly isolated i2c adapter, where the device >>driver can invite i2c drivers to connect an i2c client to. When the >>connection is made, an "interface" pointer with client-specific data >>or function pointers can be provided. >>(...) >>- add a new NO_PROBE flag to struct i2c_adapter, so a particular >>adapter is never probed by anyone > I don't get it. If the adapter is isolated, there is no way the i2c-core > will probe it anyway. As Adrian Cox underlined, it should be far easier > and more efficient to separate these adapters from the main i2c adapters > list from the beginning than leaving them in the main list and then try > and prevent future probings using a flag. There a two scenarios, where you don't have full control over the i2c adapter or you don't want to fully isolate the bus: 1) Some dvb drivers are bttv-sub-drivers, ie. bttv does the pci and i2c handling by itself. You have the struct i2c_adapter pointer, but it has been registered by bttv, most likely as an analog and/or digital tv i2c bus. 2) Embedded platforms have usually a system-wide i2c bus, so you cannot isolate the bus here. It's useful to register both adapters and drivers to the i2c-core, so you keep the door open. > Also, how does this proposal interact with the work on the i2c classes? > Although the classes carry more information than a simple flag or a > complete separation, both were/may be introduced to achieve the same > goal, isn't it? Partly, yes. The .class approach is necessary to have a finer grained access control by the i2c-core regarding bus classes, ie. not the client drivers have to check if the bus should be probed (for example dcc drivers on a dvb bus). This is useful in general. If we have a PCI card where we exactly know what we are doing, we can use the NO_PROBE flag to effectively block any probing and can use the proposed interface to manually connect the clients. > Thanks, CU Michael.
