Hi,
We have build a custom cape, with an USB 2514 hub chip[0], with several devices connected not powered by the USB, and a socket for an external battery as a power source backup.
With this scenario, we are testing the cape when power source is missing (just unpluging the 5V power source), but the hub starts to fail stating that there is no power, even with the battery connected. This are the messages we see on battery power:
Dec 2 16:18:38 baliza1 kernel: [ 2631.231775] musb-hdrc musb-hdrc.1.auto: VBUS_ERROR in a_host (91, <VBusValid), retry #1, port1 00000507
Dec 2 16:18:38 baliza1 kernel: [ 2631.449402] musb-hdrc musb-hdrc.1.auto: VBUS_ERROR in a_wait_vrise (91, <VBusValid), retry #2, port1 00000507
Dec 2 16:18:38 baliza1 kernel: [ 2631.601845] musb-hdrc musb-hdrc.1.auto: VBUS_ERROR in a_wait_vrise (91, <VBusValid), retry #3, port1 00000507
Dec 2 16:18:39 baliza1 kernel: [ 2631.754267] musb-hdrc musb-hdrc.1.auto: VBUS_ERROR in a_wait_vrise (90, <VBusValid), retry #3, port1 0008050f
Looking at the messages looks like that even with external power, it powers off the hub and the different devices connected to it. Is there any setup/workaround that we can do to avoid this problem ?
Best regards,
[0] http://www.microchip.com/DevelopmentTools/ProductDetails.aspx?PartNO=EVB-USB2514B-FS