Hi, On 06/11/2015 06:38 PM, Hans de Goede wrote: > Hi, > > On 11-06-15 11:33, Chanwoo Choi wrote: >> Hi, >> >> On 06/11/2015 05:59 PM, Hans de Goede wrote: >>> Hi, >>> >>> On 11-06-15 10:29, Chanwoo Choi wrote: >>>> Hi Hans, >>>> >>>> On 06/11/2015 05:21 PM, Hans de Goede wrote: >>>>> Hi Chanwoo, >>>>> >>>>> Thanks for the quick review. >>>>> >>>>> On 11-06-15 10:07, Chanwoo Choi wrote: >>>>>> Hi Hans, >>>>>> >>>>>> I add the comment about extcon-related code. >>>>>> >>>>>> Firstly, >>>>>> I'd like you to implment the extcon driver for phy-sun4i-usb device >>>>>> in drivers/extcon/ directoryby using MFD >>>>> >>>>> No, just no, this is not what the MFD framework is for, the usb-phy >>>>> in question here is not a multifunction device. The MFD framework >>>>> is intended for true multi-function devices like i2c attached >>>>> PMICs which have regulators, gpios, pwm, input (power button), >>>>> chargers, power-supply, etc. That is NOT the case here. >>>>> >>>>> Also moving this to the MFD framework would very likely requiring >>>>> the devicetree binding for the usb-phy to change which we cannot >>>>> do as that would break the devicetree ABI. >>>>> >>>>>> because there are both extcon >>>>>> provider driver and extcon client driver. I think that all extcon >>>>>> provider driver better to be included in drivers/extcon/ directory. >>>>>> extcon_set_cable_state() function should be handled in extcon provider >>>>>> driver which is incluced in drivers/extcon/ directory. >>>>> >>>>> I do not find this a compelling reason, there are plenty of subsystems >>>>> where not all implementations of the subsystem class live in the subsystem >>>>> directory, e.g. input and hwmon devices are often also found outside of >>>>> the input and hwmon driver directories. >>>> >>>> There are difference on between input/hwmon and extcon. >>>> >>>> Because input and hwmon driver implement the only one type driver as provider driver. >>>> But, extcon implement the two type driver of both extcon provider and extcon client driver. >>>> The extcon is similiar with regulator and clock framework as resource. >>>> >>>> extcon provider driver to provider the event when the state of external connector is changed. >>>> - devm_extcon_dev_register() >>>> - e.g., almost extcon provider driver are included in 'drivers/extcon/' directory. >>> >>> I understand, but that does not change my first argument, that the usb-phy is not >>> a MFD device. And although it may be desirable to keep extcon provider drivers >>> in the drivers/extcon, there are no technical reasons to do so. >>> >>> The whole reason why Kishon asked me to start using the extcon framework is to avoid >>> adding a private API to the phy-sun4i-usb code for notifying the musb-sunxi code >>> about otg-id-pin status changes. Adding a separate driver for just the extcon bits >>> means re-adding a private api to the phy-sun4i-usb code but this time for the >>> extcon code, at which point we might just as well skip extcon and have the >>> musb-sunxi glue code call directly into the phy-sun4i-usb code... >>> >>> Needing a private API for a separate extcn driver actually is a good argument to >>> NOT have a separate extcon driver and keep the extcon code in the phy-sun4i-usb code, >>> where as I see no technical arguments in favor of a separate extcon driver. >> >> There is one technical issue. >> >> The extcon_set_cable_state() should be handled by extcon provider driver. > > That is something which can be done regardless of where the extcon provider > driver code is located in the kernel tree... > >> because extcon_set_cable_state() inform the extcon client driver of the event >> when detecting the change of h/w line (gpio line) or register of peripheral device. >> >> But, extcon client driver can now get the instance of extcon_dev structure >> by extcon_get_edev_by_phandle() and then can change the cable state by using the extcon_set_cable_state(). >> >> I think that these issue have to be protected by framework level. > > Protecting this at the framework level would mean protecting it with code > in drivers/extcon/extcon.c, that code will be used (and thus can protect > things) regardless of where the extcon provider code lives. > > I really still see no technical reasons why all extcon provider code > MUST be under drivers/extcon. OK. As you said, this issue shold be prevented on framework. I'm considering what is appropriate method to resolve this issue. Thanks, Chanwoo Choi -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
