On Mon, Dec 19, 2011 at 04:07, Wolfgang Grandegger wg@grandegger.com wrote:
I just realized that this patch breaks "usb start" on my mx53loco board:
MX53LOCO U-Boot > usb start (Re)start USB... USB: Register 10011 NbrPorts 1 USB EHCI 1.00 scanning bus for devices... 1 USB Device(s) found scanning bus for storage devices... 0 Storage Device(s) found scanning bus for ethernet devices... 0 Ethernet Device(s) found
MX53LOCO U-Boot > usb start (Re)start USB... USB: Register 10011 NbrPorts 1 USB EHCI 1.00 scanning bus for devices... 2 USB Device(s) found scanning bus for storage devices... 0 Storage Device(s) found scanning bus for ethernet devices... 1 Ethernet Device(s) found
The device is not found at the first attempt. Obviously, a value of 10 for bPwrOn2PwrGood seems too short but 20 works fine. Would that be a resonable compromise? If yes, I could send a patch.
This doesn't match the EHCI standard which explicity states that the power should be good after 20ms (paragraph 2.3.9 in EHCI 1.0), so we should probably find whether we are missing another delay somewhere in the generic EHCI code (which used to be hidden and should be fixed) or if i.MX53 is not compliant with the standard and need a special quirk.