Hi, On Tue, Feb 19, 2013 at 12:33:54PM +0000, Arnd Bergmann wrote: > On Tuesday 19 February 2013, kishon wrote: > > On Tuesday 19 February 2013 04:14 PM, Arnd Bergmann wrote: > > > On Tuesday 19 February 2013, Kishon Vijay Abraham I wrote: > > >> Added a generic PHY framework that provides a set of APIs for the PHY drivers > > >> to create/destroy a PHY and APIs for the PHY users to obtain a reference to > > >> the PHY with or without using phandle. To obtain a reference to the PHY > > >> without using phandle, the platform specfic intialization code (say from board > > >> file) should have already called phy_bind with the binding information. The > > >> binding information consists of phy's device name, phy user device name and an > > >> index. The index is used when the same phy user binds to mulitple phys. > > >> > > >> This framework will be of use only to devices that uses external PHY (PHY > > >> functionality is not embedded within the controller). > > >> > > >> The intention of creating this framework is to bring the phy drivers spread > > >> all over the Linux kernel to drivers/phy to increase code re-use and to > > >> increase code maintainability. > > >> > > >> Comments to make PHY as bus wasn't done because PHY devices can be part of > > >> other bus and making a same device attached to multiple bus leads to bad > > >> design. > > > > > > How does this relate to the generic PHY interfaces in drivers/net/phy? > > > > Currently drivers/phy and drivers/net/phy are independent and are not > > related to each other. There are some fundamental differences on how > > these frameworks work. IIUC, the *net* uses bus layer (MDIO bus) to > > match a PHY device with a PHY driver and the Ethernet device uses the > > bus layer to get the PHY. > > The Generic PHY Framework however doesn't have any bus layer. The PHY > > should be like any other Platform Devices and Drivers and the framework > > will provide some APIs to register with the framework. And there are > > other APIs which any controller can use to get the PHY (for e.g., in the > > case of dt boot, it can use phandle to get a reference to the PHY). > > Hmm, I think the use of a bus_type for a PHY actually sounds quite > appropriate. The actual PHY device would then be a child of the really ? I'm not so sure, the *bus* used by the PHY is ULPI, UTMI, UTMI+, PIP3, I2C, etc... adding another 'fake' bus representation is a bit overkill IMO. Imagine an I2C-controlled PHY driver like isp1301, that driver will have to register i2c_driver and phy_driver, which looks weird to me. If the only substitute for class is a bus, we can't drop classes just yet, I'm afraid. Imagine a regulator bus, a pwm bus, an LED bus etc. They don't make sense IMHO. > platform_device (or something else) that gets probed by its parent > bus or the DT. The operations that you define for the PHY > actually mirror some of the things that we have for a 'struct device', > so I think it would be quite logical to do it the same way. > > Note that MDIO has both a 'bus' and a 'class', and what we want here is more > like what the 'class' was meant for, except that for new classes, we > should actually use a 'bus', since the long-term plan is to kill off > the concept of a 'class'. I hope that was not too confusing. :) :) -- balbi
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