Hi Wolfgang, 2011/12/19 Wolfgang Grandegger <w...@grandegger.com>: > 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: >>> >>> 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
I would prefer a solution in line with the specification, but what is the reason why Linux takes 100 msec here? Is that just chosen randomly , or was there a good reason for it? If there is a good reason (which I assume) I would prefer to follow Linux here and go for the 100 msec. Can you please provide a patch? Kind regards, Remy _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot