29 May
2014
29 May
'14
11:25 p.m.
On 05/19/2014 02:21 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
usb_hub_power_on() currently waits for the maximum of (a) the hub port's power output to become good, (b) the max time the USB specification allows a device to take to connect.
However, these two operations must occur in series rather than in parallel. First, the power supply ramps up to the level required to power the USB device, and then the device may take a certain amount of time to connect (assert D+/D- pullups).
Related, the maximum time that a device has to assert pullups is 1s not 100ms.
This is explained in "Connect Timing ECN.pdf", itself part of usb_20_042814.zip from www.usb.org.
Marek, does this series look OK?