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v4.14.11: USB_VBUS and hardware watchdog wont work independent with gadget RNDIS

Posted: Thu Jun 14, 2018 12:38 pm
by PowerPenguin
Hi *,

we have an issue with the USB_VBUS of USB gadget and hardware GPIO watchdog trigger (1.6sec):

SoC: AT91SAM9g20

A) USB device RNDIS is plugged => everything fine
B) If we unplug USB gadget cable in Linux, the watchdog stops toggling in about 10sec
C) If we power up and boot Linux without plugged USB cable. We can see that GPIO watchdog early init toggles 4 times and then stops. WD reboot !
(uncompression of kernel and early WD init is done in 0.7sec and then we toggle. )
D) if we remove /* atmel,vbus-gpio = <&pioC 15 GPIO_ACTIVE_HIGH>; */ from device tree we have no issue

Questions:
1) What could be the problem inside the Micochip AT91 clock / irq system ?
2) plug and unplug of RNDIS works with out USB_VBUS in device tree. For what is USB_VBUS (device port) required ?