On 02/19/2013 04:05 PM, Felipe Balbi wrote: > 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. You have the code for phy <-> device matching in your framework anyway. Using the bus infrastructure brings changes the open coded matching into bus callbacks. regards, Marc -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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