On Mon, Nov 5, 2012 at 10:12 AM, Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > On Mon, Nov 05, 2012 at 04:19:20PM +0100, Jean Delvare wrote: >> On Mon, 5 Nov 2012 16:53:15 +0200, Mika Westerberg wrote: >> > On Mon, Nov 05, 2012 at 03:19:58PM +0100, Rafael J. Wysocki wrote: >> > > >> > > In the ACPI namespace we have device nodes and serial interfaces below them. >> > > In the above case we see that a single device node supports two different >> > > interfaces and in that case we probably should create two different >> > > struct i2c_adapter objects for the same ACPI device node. >> > > >> > > Mika, what do you think? >> > >> > I agree. >> > >> > Only problem I see is that then we have two I2C adapter devices with the >> > same ACPI ID (and hence the same i2c_client->name). I wonder what the I2C >> > core thinks about that. >> >> I2C core fears that you're mixing up everything ;) I2C adapter devices >> are struct i2c_adapter aka i2c-0, i2c-1 etc. i2c_client is for slave >> devices. There's nothing wrong with i2c_clients sharing ->name, that's >> even how device driver matching is achieved. The uniqueness of >> i2c_clients is on their bus_id which is the combination of i2c adapter >> number and slave address (e.g. 0-0050) > > Yeah, I mixed I2C adapter and client. Thanks for correcting. > > So if we create one I2C adapter from the platform bus code as we do now and > then for each I2CSerialBus connector we create one I2C client (well, the > one that is created when i2c_new_device() is called), everything should > work, right? > > Then I suggest that we have a list of serial bus resources in the struct > acpi_device and create the I2C clients based on that. > >> i2c_adapter->name should, OTOH, be unique. In i2c bus drivers we >> usually append the base I/O address at the end of the name to guarantee >> that. ACPI will have to come up with something similar. > > It should already be unique in case of ACPI. We use ACPI _HID and _UID to > achieve that. Using only _HID and _UID to guarantee uniqueness means you're relying on a property of the BIOS, so you're vulnerable to BIOS bugs. If there's an ACPI Device for I2C adapters, why wouldn't you just use its device name as set in acpi_device_register() (basically a _HID + instance number)? -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
