On 16 June 2017 at 07:31, Bin Meng bmeng.cn@gmail.com wrote:
Occasionally it was observed that on Intel MinnowMax board, with a USB 2.0 device connected to the bottom port, when doing 'usb start' on the xHCI controller:
scanning bus 0 for devices... cannot reset port 3!?
But neither of the two USB ports is routed to xHCI root port 3. Adding some debug information shows that xHCI port 3 PORTSC register mysteriously reports both CCS = 1 and CSC = 1.
This is not seen every time. After increasing the timeout to wait for power to become stable, the issue is gone. So this indicates current default USB power-on delay (20ms) might be at a critical region where power is stable/unstable. U-Boot provides a mechanism to have a environment variable to override the default one. Add one for MinnowMax.
Signed-off-by: Bin Meng bmeng.cn@gmail.com
include/configs/minnowmax.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
Reviewed-by: Simon Glass sjg@chromium.org