Hi Felipe, All, While working with the webcam gadget in recent past I came to realize that if the webcam gadget is compiled as a static part of the kernel, the USB webcam device when connected to the USB host will not successfully enumerate (as the USB host will send a GET_DEF class specific UVC request), which is handled by a user-space application responsible for ensuring command/data flow between the UVC gadget and a real V4L2 device. I believe similar will be the case for other gadgets like obex while working with an underlying UDC during the start-up phase (during the enumeration process). Gadgets like webcam/obex explicitly call the 'pullup' routine of the underlying UDC (with is_on argument set to 0) to issue soft-disconnect command at the very start. This is done to prevent the enumeration process to proceed unless a supporting user-space application is first up and running (which can handle the class-specific control requests on the basis of certain negotiations with other entities, like for e.g. a real video device in case of webcam). (see [1] for reference). However with the current framework (newstyle UDC) just after the 'bind' of the function (f_uvc/f_obex) is called, the UDC framework calls the 'pullup' routine of the UDC again with a parameter is_on set to 1 to initiate connection with the Host. (see [2] for reference). This seems to be an incorrect implementation as it causes the enumeration to start even for gadgets like webcam/obex which have explicitly requested only a soft-connect (as the user-space application has not been launched yet). Please let me know your ideas on the same. At the moment I have used a temporary approach like the one given below (though it is in no way a very good way out :) ). [1] http://lxr.linux.no/linux+v3.4.4/drivers/usb/gadget/f_uvc.c#L548 [2] http://lxr.linux.no/linux+v3.4.4/drivers/usb/gadget/udc-core.c#L341 Signed-off-by: Bhupesh Sharma <bhupesh.sharma@xxxxxx> --- drivers/usb/dwc3/core.h | 1 + drivers/usb/dwc3/gadget.c | 24 ++++++++++++++++++------ drivers/usb/gadget/udc-core.c | 19 ++++++++++++++++++- include/linux/usb/gadget.h | 1 + 4 files changed, 38 insertions(+), 7 deletions(-) diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h index 2d8676c..9125ec9 100644 --- a/drivers/usb/dwc3/core.h +++ b/drivers/usb/dwc3/core.h @@ -712,6 +712,7 @@ struct dwc3 { struct dwc3_hwparams hwparams; struct dentry *root; + bool deactivated_at_start; u8 test_mode; u8 test_mode_nr; diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index b82fe61..0d6ea17 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1341,6 +1341,12 @@ static const struct usb_ep_ops dwc3_gadget_ep_ops = { }; /* -------------------------------------------------------------------------- */ +static bool dwc3_gadget_is_deactivated_at_start(struct usb_gadget *g) +{ + struct dwc3 *dwc = gadget_to_dwc(g); + + return dwc->deactivated_at_start; +} static int dwc3_gadget_get_frame(struct usb_gadget *g) { @@ -1448,6 +1454,7 @@ static void dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on) { u32 reg; u32 timeout = 500; + static bool first_deactivation; reg = dwc3_readl(dwc->regs, DWC3_DCTL); if (is_on) { @@ -1461,6 +1468,10 @@ static void dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on) reg |= DWC3_DCTL_RUN_STOP; } else { reg &= ~DWC3_DCTL_RUN_STOP; + if (first_deactivation == false) { + dwc->deactivated_at_start = true; + first_deactivation = true; + } } dwc3_writel(dwc->regs, DWC3_DCTL, reg); @@ -1600,12 +1611,13 @@ static int dwc3_gadget_stop(struct usb_gadget *g, } static const struct usb_gadget_ops dwc3_gadget_ops = { - .get_frame = dwc3_gadget_get_frame, - .wakeup = dwc3_gadget_wakeup, - .set_selfpowered = dwc3_gadget_set_selfpowered, - .pullup = dwc3_gadget_pullup, - .udc_start = dwc3_gadget_start, - .udc_stop = dwc3_gadget_stop, + .is_deactivated_at_start = dwc3_gadget_is_deactivated_at_start, + .get_frame = dwc3_gadget_get_frame, + .wakeup = dwc3_gadget_wakeup, + .set_selfpowered = dwc3_gadget_set_selfpowered, + .pullup = dwc3_gadget_pullup, + .udc_start = dwc3_gadget_start, + .udc_stop = dwc3_gadget_stop, }; /* -------------------------------------------------------------------------- */ diff --git a/drivers/usb/gadget/udc-core.c b/drivers/usb/gadget/udc-core.c index a6ebeec..c42ea92 100644 --- a/drivers/usb/gadget/udc-core.c +++ b/drivers/usb/gadget/udc-core.c @@ -261,6 +261,13 @@ static int udc_is_newstyle(struct usb_udc *udc) return 0; } +static int udc_is_deactivated_at_start(struct usb_udc *udc) +{ + if (udc->gadget->ops->is_deactivated_at_start) + return udc->gadget->ops->is_deactivated_at_start(udc->gadget); + + return 0; +} static void usb_gadget_remove_driver(struct usb_udc *udc) { @@ -355,7 +362,17 @@ found: driver->unbind(udc->gadget); goto err1; } - usb_gadget_connect(udc->gadget); + + /* + * do not connect if the function has requested an + * explicit disconnect at the very start and hence + * does not want to connect unless a user-space application + * explicitly calls the 'function_activate' routine + * to connect (this is required in case of certain + * functions like obex and webcam). + */ + if (!udc_is_deactivated_at_start(udc)) + usb_gadget_connect(udc->gadget); } else { ret = usb_gadget_start(udc->gadget, driver, bind); diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h index 665b1d1..4c4e665 100644 --- a/include/linux/usb/gadget.h +++ b/include/linux/usb/gadget.h @@ -507,6 +507,7 @@ struct usb_gadget_driver; * which don't involve endpoints (or i/o). */ struct usb_gadget_ops { + bool (*is_deactivated_at_start)(struct usb_gadget *); int (*get_frame)(struct usb_gadget *); int (*wakeup)(struct usb_gadget *); int (*set_selfpowered) (struct usb_gadget *, int is_selfpowered); -- 1.6.0.2 Regards, Bhupesh -- 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
