On 12/19/2011 01:51 PM, Vincent Palatin wrote: > On Mon, Dec 19, 2011 at 04:07, Wolfgang Grandegger <w...@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.
I'm not an USB expert but if I look into the hub_power_on() function of the Linux kernel it waits at least 100ms (and only once). See: http://lxr.linux.no/#linux+v3.1.5/drivers/usb/core/hub.c#L567 Wolfgang. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
