On 06/11/2015 06:33 PM, 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. > 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. I fix wrong word. (protected -> prevented) - I think that these issue have to be prevented by framework level. 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
