Chanwoo & Robert, On 20/03/15 09:45, Chanwoo Choi wrote: > Hi Robert, > > On 03/20/2015 04:25 PM, Robert Baldyga wrote: >> Hi Chanwoo, >> >> On 03/19/2015 09:50 PM, Chanwoo Choi wrote: >>> Hi Roger, >>> >>> On Thu, Mar 19, 2015 at 11:45 PM, Roger Quadros <rogerq@xxxxxx> wrote: >>>> On 19/03/15 14:19, George Cherian wrote: >>>>> Hi Robert, >>>>> >>>>> +Roger >>>>> On Thu, Mar 19, 2015 at 5:37 PM, Robert Baldyga <r.baldyga@xxxxxxxxxxx> wrote: >>>>>> Hi George, >>>>>> >>>>>> On 03/19/2015 09:50 AM, George Cherian wrote: >>>>>>> Hi Robert, >>>>>>> >>>>>>> This looks like a extcon driver based on gpio for USB. >>>>>>> >>>>>>> Roger posted a generic one a while back. >>>>>>> https://lkml.org/lkml/2015/2/2/187 >>>>>>> >>>>>>> Doesn't this serve the purpose rather than adding this driver? >>>>>> >>>>>> Roger's driver doesn't support VBUS state detection so it cannot handle >>>>> I feel Roger's driver could be extended for supporting VBUS. >>>>> Also I think Roger's driver is about to get merged. >>>>> Probably, Roger or Chanwoo can better tell that >>>> >>>> It is already queued for 4.1 and is available in linux-next. >>>> >>>>> >>>>>> situation when USB cable is unpluged. In addition some of Odroid boards >>>>>> has only VBUS detection (without ID pin), so this driver cannot handle >>>>>> them at all. >>>> >>>> why not? >>>> >>>> x15-beagleboard also gets VBUS event over GPIO and I was planning to extent it >>>> to support VBUS detection. >>> >>> Sounds good to me to extent extcon-usb-gpio.c. >>> I'd like to hold only one extcon driver to support both USB and >>> USB-HOST with gpio . >>> >>> There are one more extcon-gpio driver in mailing list as following: >>> - extcon-usb-gpio.c (will be merged to Linux 4.1) >>> - extcon-odroid-usbotg.c >>> - extcon-otg_gpio.c [1] >>> [1] https://lkml.org/lkml/2015/2/19/411 >>> >>> The each extcon gpio driver support both USB/USB-HOST cable by using >>> different way, >>> Because some board which detect USB/USB-HOST by gpio have a little >>> different pin composition >> >> These differences are small. In general we have three cases: >> >> 1. We have both VBUS and ID pin detection - we can detect USB, USB-HOST >> and cable disconnection. >> >> 2. We have only VBUS detection - we can detect USB and cable disconnection. >> >> 3. We have ID pin only - we can distinguish between USB and USB-HOST but >> without ability to detect cable disconnection. >> >>> >>> I think only one extcon driver can support all cases with optional properties. >> >> So my driver in current form is ready for that. Only thing it would need >> to change is to make VBUS detection an option (for now is mandatory >> because all of supported Odroid boards have it). Then boards with VBUS >> detection only or ID pin detection only will be handled also. I can also >> change name of the driver to more generic. I'm going to prepare V2 on my >> patches today. > > Could you implement this feature on extcon-usb-gpio.c to support various pin composition? > because extcon-usb-gpio.c was already implemented by Roger. > If you implement other extcon driver to detect USB/USB-HOST cable by using gpio, > there will be similar two extcon gpio driver for USB cable. > > And, > As Roger comment, he have the plan to extend the extcon-usb-gpio.c. > So, If you will implement some feature for extcon driver with gpio, > I'd like you to share your plan this thread to remove duplicat work. extcon-usb-gpio.c supports case (3). (only ID pin) I have plans to support case (1). (both ID and VBUS) But Robert can go ahead and implement (2) and (1) over extcon-usb-gpio.c if he wishes. The driver can easily decide which logic to follow depending on the availability of the GPIO pins in the device tree. cheers, -roger -- 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
