tree ee471aefd5be3cf396cadba0aebc1ab117871ace
parent 9547e419eb1df6e75db4af7b9f3ea4061f4d3e1e
author Kévin Redon <kredon@sysmocom.de> 1533571040 +0200
committer Kévin Redon <kredon@sysmocom.de> 1533636589 +0200

USB: increase USB reset time

USB reset can be signaled by pulling low USB D+ for at least 10 ms,
according to the USB specification. This force a re-enumeration.
This time is increased to 20 ms to work with more USB HUBs.

Some SAM3S based board have external D+ pull-up mechanism (such as
SIMtrace) which needs to be used to pull D+ low.
This is a legacy mechanism from SAM7S history.
This mechanism is not required anymore on the SAM3S, and the qmod
does not use it. When the USB HAL is suspended, the transceiver is
disabled, causing D+ and D- to be pulled low. Then the HAL is activated
again. This is particularly required when DFU is started (and
enumerated), and after flashing the SAM3S switched to the main
application (without reset), so it can properly re-enumerate.

This board difference is now defined on the board header.

Change-Id: I9b58d8101c2fcf5595026b675728826af26127a3