USB and suspend. Will it still charge?

Andy Green andy at
Wed Apr 23 09:54:24 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
| Hi,
| --- Carsten Haitzler (The Rasterman) wrote:
| | concern is:
| |
| | we plug in, phone wakes. phone gets bored. phone goes to sleep. uspend
| | happens.
| | pc detects device removal. pc powers down usb port. phone does not
| | have power
| | from usb. no charging happens.
| \--
| The specifications are here:
| "If a portable device is attached to a hub or host charger, it is
| allowed to draw a current of IDEV_HCHGR_LFS or IDEV_HCHGR_HS,
| regardless of suspend".
| "If a portable device is attached to a USB host or hub, then the USB
| 2.0 spec requires that:
| * after connecting a portable device must draw less than
|     * 2.5mA average if the bus is suspended".

Nice work.  I see the "initial release" was end of March 2007, it seems
we didn't find out about this until a bit late.  This is the document
that says USB chargers should short D+ and D-.

What this seems to be saying is that we should adapt our device charging
status according to whether the HOST PC goes into suspend, I don't think
we do this right now.

- -Andy
Version: GnuPG v1.4.9 (GNU/Linux)
Comment: Using GnuPG with Fedora -


More information about the openmoko-kernel mailing list