On Wed, May 17, 2023 at 10:19:25AM -0700, Badhri Jagan Sridharan wrote:
On Wed, May 17, 2023 at 7:44 AM Alan Stern stern@rowland.harvard.edu wrote:
On Wed, May 17, 2023 at 11:59:55AM +0000, Badhri Jagan Sridharan wrote:
chipidea udc calls usb_udc_vbus_handler from udc_start gadget ops causing a deadlock. Avoid this by offloading usb_udc_vbus_handler processing.
Surely that is the wrong approach.
The real problem here is that usb_udc_vbus_handler() gets called from within a udc_start routine. But this is totally unnecessary, because the UDC core will call usb_udc_connect_control_locked() itself, later on during gadget_bind_driver().
Hi Alan,
usb_udc_vbus_handler sets the udc->vbus flag as well apart from calling usb_udc_connect_control_locked(). So, removing usb_udc_vbus_handler from chip specific start callback might prevent the controller from starting.
void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status) { struct usb_udc *udc = gadget->udc;
mutex_lock(&udc->connect_lock); if (udc) { udc->vbus = status; usb_udc_connect_control_locked(udc);
Then add "udc->vbus = true;" at the appropriate spot in gadget_bind_driver().
Alan Stern
PS: I just noticed that in max3420_udc.c, the max_3420_vbus_handler() function calls usb_udc_vbus_handler() from within an interrupt handler. This won't work, since interrupt handlers aren't allowed to sleep and therefore can't lock mutexes.