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-rw-r--r--common/usb_hub.c19
1 files changed, 16 insertions, 3 deletions
diff --git a/common/usb_hub.c b/common/usb_hub.c
index 2add4b9..c416e5e 100644
--- a/common/usb_hub.c
+++ b/common/usb_hub.c
@@ -209,9 +209,22 @@ int hub_port_reset(struct usb_device *dev, int port,
(portstatus & USB_PORT_STAT_CONNECTION) ? 1 : 0,
(portstatus & USB_PORT_STAT_ENABLE) ? 1 : 0);
- if ((portchange & USB_PORT_STAT_C_CONNECTION) ||
- !(portstatus & USB_PORT_STAT_CONNECTION))
- return -1;
+ /*
+ * Perhaps we should check for the following here:
+ * - C_CONNECTION hasn't been set.
+ * - CONNECTION is still set.
+ *
+ * Doing so would ensure that the device is still connected
+ * to the bus, and hasn't been unplugged or replaced while the
+ * USB bus reset was going on.
+ *
+ * However, if we do that, then (at least) a San Disk Ultra
+ * USB 3.0 16GB device fails to reset on (at least) an NVIDIA
+ * Tegra Jetson TK1 board. For some reason, the device appears
+ * to briefly drop off the bus when this second bus reset is
+ * executed, yet if we retry this loop, it'll eventually come
+ * back after another reset or two.
+ */
if (portstatus & USB_PORT_STAT_ENABLE)
break;