[android-developers] Re: Prevent Android USB Host (OTG) from suspend

I'm not sure you can "just ignore" it. In fact, you probably can't.
It's telling you that you WILL be suspended and that you should do
something. If the host then reduces power (down to 500 uA is allowed,
or 2.5 mA if you are a remote wake-up device) then you are in trouble.
The USB spec requires a suspend mode for all compliant devices (if you
want a USB certified sticker).

You can exceed this low limit for short periods of time, but the
average needs to be below that (and the averaging window is one
second, I believe). If you can get in and modify the kernel/USB driver
to not go into suspend,

Finally, if you get a suspend command but the system does not lower
the power on you, then it's not doing the right thing. Don't bank on
this behavior if you are trying to create a system that will work on a
wide variety of devices. If you only care about the Xoom or another
specific box, fine, but in general this will not work.

On Mar 19, 12:20 pm, Sebastian <mail.sebastian.schu...@googlemail.com>
wrote:
> Okay thanks for your help.
>
> Seems like the Xoom sends a USB suspend command, but still sources (enough)
> power.
> In contrast to that, my Galaxy Nexus does not send a suspend command.
>
> So I will probably just ignore the suspend command...
>
> Am Montag, 19. März 2012 11:16:09 UTC+1 schrieb Mark Murphy (a Commons Guy):
>
>
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>
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>
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>
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> > On Mon, Mar 19, 2012 at 4:38 AM, Sebastian
> > > Since I absolutely need to have 'full power' all the time, please help me
> > > and post some hints how I could prevent the USB host to go to suspend
> > mode.
> > > I tried a full wake lock, but it didn't help :(
>
> > With a full WakeLock, the screen does not turn off. Are you saying
> > that the power dropped anyway after some period of time?
>
> > Regardless, this sounds like it might be XOOM-specific, in which case
> > you may be better served asking over on the MOTODEV support boards.
>
> > --
> > Mark Murphy (a Commons Guy)
> >http://commonsware.com|http://github.com/commonsguy
> >http://commonsware.com/blog|http://twitter.com/commonsguy
>
> > _The Busy Coder's Guide to *Advanced* Android Development_ Version 2.5
> > Available!

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