[LAU] Teufel PC Bamster not getting connected on USB?

[David Kastrup]

Clemens Ladisch <clemens-P6GI/4k7KOmELgA04lAiVw at public.gmane.org>
writes:

> David Kastrup wrote:
>> Or it talks with the host and says "I want 1A of current or 2A" and the
>> host says "no way".
>
> Its descriptors claim that it wants 0 mA.
>
>> But it's delivered by default with a two-host-plug USB cable
>
> So it needs more power than a single plug could supply?

Ostensibly it's 2x5W of output.  It runs without complaint on a single
plug when using Analog In, and shuts down in USB mode.  I doubt that the
digital part takes up more than one plug can deliver...

>> and would not be able to know about the power available from the
>> power-only plug.  And it doesn't complain when running from the analog
>> input either, so it would be somewhat strange to just shut down when in
>> USB mode.
>
> After a short time, it just stops reacting to USB requests.
>
> It might be possible that some capacitor does no longer work correctly,
> and that its internal voltage drops too far when actually doing things.
> This would imply that it doesn't work in Windows either.

Well, the Windows PC disagrees.  And the thing obviously has a whole lot
more volume reserves in USB mode: apparently the AUX in levels are badly
matched to typical sources.

I tried disabling autosuspend on USB by blacklisting in /etc/default/tlp
but it doesn't seem to help:

+++ USB
Autosuspend        = enabled
Device whitelist   = (not configured)
Device blacklist   = 04a9:220e 10d6:1100
WWAN blacklist     = enabled

Bus 002 Device 030 ID 07c4:a827 control = auto, autosuspend_delay_ms =  2000 -- Datafab Systems, Inc.  (usb-storage)
Bus 002 Device 001 ID 1d6b:0002 control = auto, autosuspend_delay_ms =     0 -- Linux Foundation 2.0 root hub (hub)
Bus 007 Device 001 ID 1d6b:0001 control = auto, autosuspend_delay_ms =     0 -- Linux Foundation 1.1 root hub (hub)
Bus 006 Device 001 ID 1d6b:0001 control = auto, autosuspend_delay_ms =     0 -- Linux Foundation 1.1 root hub (hub)
Bus 005 Device 032 ID 10d6:1100 control = on,   autosuspend_delay_ms =  2000 -- Actions Semiconductor Co., Ltd MPMan MP-Ki 128 MP3 Player/Recorder (snd-usb-audio)
Bus 005 Device 001 ID 1d6b:0001 control = auto, autosuspend_delay_ms =     0 -- Linux Foundation 1.1 root hub (hub)
Bus 001 Device 001 ID 1d6b:0002 control = auto, autosuspend_delay_ms =     0 -- Linux Foundation 2.0 root hub (hub)
Bus 004 Device 001 ID 1d6b:0001 control = auto, autosuspend_delay_ms =     0 -- Linux Foundation 1.1 root hub (hub)
Bus 003 Device 001 ID 1d6b:0001 control = auto, autosuspend_delay_ms =     0 -- Linux Foundation 1.1 root hub (hub)

(tricky to time switching it on at the right moment so that tlp-stat
will see it before it turns off again).  Switching autosuspend off
altogether does not help either.

Powered hub in the middle: the Boomster stays on _until_ I connect the
hub to the laptop.  Then it identifies itself to the laptop and switches
off.

Really does not sound to me like it's an issue of digital power: then it
should not work under Windows I think, even granted that this is quite a
different type of laptop.

-- 
David Kastrup