On Wed, Apr 06, 2011 at 09:59:02PM +0300, Felipe Balbi wrote: > Hi, > > On Wed, Apr 06, 2011 at 08:47:34PM +0200, Samuel Ortiz wrote: > > > > > What is a "MFD cell pointer" and why is it needed in struct device? > > > > An MFD cell is an MFD instantiated device. > > > > MFD (Multi Function Device) drivers instantiate platform devices. Those > > > > devices drivers sometimes need a platform data pointer, sometimes an MFD > > > > specific pointer, and sometimes both. Also, some of those drivers have been > > > > implemented as MFD sub drivers, while others know nothing about MFD and just > > > > expect a plain platform_data pointer. > > > > > > That sounds like a bug in those drivers, why not fix them to properly > > > pass in the correct pointer? > > Because they're drivers for generic IPs, not MFD ones. By forcing them to use > > MFD specific structure and APIs, we make it more difficult for platform code > > to instantiate them. > > I agree. What I do on those cases is to have a simple platform_device > for the core IP driver and use platform_device_id tables to do runtime > checks of the small differences. If one platform X doesn't use a > platform_bus, it uses e.g. PCI, then you make a PCI "bridge" which > allocates a platform_device with the correct name and adds that to the > driver model. > > See [1] (for the core driver) and [2] (for a PCI bridge driver) for an > example of what I'm talking about. Yes, thanks for providing a real example, this is the best way to handle this. thanks, greg k-h -- 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
