Hi, On Tue, Feb 19, 2013 at 02:34:40PM +0000, Arnd Bergmann wrote: > On Tuesday 19 February 2013, Felipe Balbi wrote: > > On Tue, Feb 19, 2013 at 12:33:54PM +0000, Arnd Bergmann wrote: > > > > 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. > > It's a fine line, but I think a phy is something that resembles a device > more than an LED does. When I read patch 1, I also noticed and commented > on the fact that it does use a 'class'. Now, according to Greg, we should > use 'bus_type' instead of 'class' in new code. I originally disagreed with > that concept, but he's the boss here and it's good if he has a vision > how things should be lined out. > > In practice, there is little difference between a 'bus_type' and a 'class', > so just replace any instance of the former with the latter in your head > when reading the code ;-) it's not so simple :-) if we must use bus_type we need to introduce all the device/driver matching mechanism which isn't necessary with a class. > I understand that there is not a real common bus here, and the bus_type > infrastructure would basically be used as a way to represent each PHY > in sysfs and provide a way to enumerate and look them up inside of the > kernel. right, but maybe we need another mechanism. If, in the long run we must use bus_type, then eventually pwm, led, regulators, etc will all be converted to bus_type. It will look quite weird IMHO. Greg, can you pitch your suggestion here ? It would be great to hear your rationale behind dropping class infrastructure, couldn't find anything through Google and since feature-removal-schedule.txt has been removed (without adding it to feature-removal-schedule.txt, I must add :-) I don't know what's the idea behind removing classes. cheers -- balbi
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