From: Robert Hancock <hancockr@shaw.ca>
To: linux-kernel <linux-kernel@vger.kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Subject: Re: USB devices fail unnecessarily on unpowered hubs
Date: Thu, 01 Jun 2006 17:37:01 -0600 [thread overview]
Message-ID: <447F7A1D.3070906@shaw.ca> (raw)
In-Reply-To: <6iYQx-5Jc-7@gated-at.bofh.it>
Alan Stern wrote:
>>
>> (Goes away and pats all his 240V plugpacks which are happily working off 110V).
>
> They probably will. The question is, how far out-of-spec should the
> kernel allow by default? 200% is likely to be too far (your plugpacks
> notwithstanding).
I would say by default the kernel should not allow any out-of-spec power
condition. Some devices might decide to go into over-current mode if a
device draws too much power, taking down other devices on the USB bus.
This sort of behavior should only be enabled if the user explicitly
chooses to live dangerously.
Especially given the fact that Windows enforces the USB power supply
limits strictly, and that's where all the hardware is best tested..
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/
next parent reply other threads:[~2006-06-01 23:37 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <6iYGP-5hv-3@gated-at.bofh.it>
[not found] ` <6iYQx-5Jc-7@gated-at.bofh.it>
2006-06-01 23:37 ` Robert Hancock [this message]
[not found] <6kl8h-1Uf-15@gated-at.bofh.it>
2006-06-07 0:51 ` USB devices fail unnecessarily on unpowered hubs Robert Hancock
2006-06-05 11:07 Lee Dowling
-- strict thread matches above, loose matches on Subject: below --
2006-06-02 15:11 [linux-usb-devel] " Alan Stern
2006-06-02 19:49 ` David Liontooth
[not found] <6iWP5-2gj-71@gated-at.bofh.it>
[not found] ` <6iX82-2UJ-3@gated-at.bofh.it>
2006-06-01 23:35 ` Robert Hancock
2006-06-01 23:46 ` Randy.Dunlap
2006-06-01 9:18 David Liontooth
2006-05-30 20:01 ` Pavel Machek
2006-06-03 9:29 ` Oliver Neukum
2006-06-01 10:01 ` Andrew Morton
2006-06-01 11:42 ` Daniel Drake
2006-06-01 14:58 ` Alan Stern
2006-06-01 15:09 ` linux-os (Dick Johnson)
2006-06-01 15:23 ` Lennart Sorensen
2006-06-01 21:39 ` Dagfinn Ilmari Mannsåker
2006-06-01 15:53 ` Oliver Neukum
2006-06-01 17:24 ` linux-os (Dick Johnson)
2006-06-01 16:57 ` Alan Stern
2006-06-01 16:59 ` Andrew Morton
2006-06-01 17:08 ` Alan Stern
2006-06-01 17:34 ` Mark Lord
2006-06-01 17:47 ` Alan Stern
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