From: Peter Stuge <peter-Y+HMSxxDrH8@public.gmane.org>
To: Alan Stern <stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org>
Cc: Sarah Sharp
<sarah.a.sharp-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
Dan Williams <dcbw-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Lan Tianyu <tianyu.lan-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
lenb-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org,
linux-acpi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [RFC PATCH] usb/acpi: Add support usb port power off mechanism for device fixed on the motherboard
Date: Fri, 11 May 2012 16:30:27 +0200 [thread overview]
Message-ID: <20120511143027.8313.qmail@stuge.se> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1205111019000.1865-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
Alan Stern wrote:
> > > Maybe we need an "off" setting that forces the port off?
> >
> > FWIW this would be very welcome in libusb, to do a hard reset of
> > bus-powered devices.
> >
> > It can be attempted via SET_FEATURE(PORT_POWER) to the hub, but a
> > "real" API would be nice.
>
> But remember that such an API would be very unreliable. Many hubs and
> root hubs cannot shut off port power at all, and some of the remaining
> ones use ganged power switches (you have to turn off all the ports in a
> gang before power is removed from any of them).
Yes, I know. It would be extra special nice if the kernel exposes
these various capabilities, in case they are already known.
//Peter
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next prev parent reply other threads:[~2012-05-11 14:30 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-10 8:33 [RFC PATCH] usb/acpi: Add support usb port power off mechanism for device fixed on the motherboard Lan Tianyu
2012-05-10 15:54 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.1205101136470.1831-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2012-05-10 16:35 ` Sarah Sharp
2012-05-10 17:44 ` Alan Stern
2012-05-11 16:12 ` Lan Tianyu
2012-05-11 16:16 ` Lan Tianyu
2012-05-11 17:44 ` Alan Stern
2012-05-11 18:12 ` Sarah Sharp
2012-05-12 12:47 ` Sergei Shtylyov
2012-05-12 14:04 ` Greg KH
2012-05-12 18:00 ` Lan Tianyu
2012-05-11 18:18 ` Lan Tianyu
[not found] ` <Pine.LNX.4.44L0.1205111302080.1865-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2012-05-11 18:35 ` Greg KH
2012-05-11 19:32 ` Alan Stern
2012-05-11 20:11 ` Sarah Sharp
2012-05-11 21:09 ` Peter Stuge
2012-05-15 1:47 ` Sarah Sharp
2012-05-15 4:57 ` Peter Stuge
2012-05-11 19:54 ` Lan, Tianyu
2012-05-11 20:15 ` Sarah Sharp
2012-05-11 20:26 ` Alan Stern
2012-05-11 20:20 ` Alan Stern
2012-05-12 17:47 ` Lan Tianyu
2012-05-12 18:04 ` Lan Tianyu
2012-05-13 2:50 ` Alan Stern
2012-05-10 19:19 ` Dan Williams
[not found] ` <1336677578.6463.5.camel-wKZy7rqYPVb5EHUCmHmTqw@public.gmane.org>
2012-05-10 21:11 ` Sarah Sharp
2012-05-11 4:13 ` Peter Stuge
2012-05-11 14:20 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.1205111019000.1865-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2012-05-11 14:30 ` Peter Stuge [this message]
2012-05-11 14:08 ` Alan Stern
2012-05-11 18:03 ` Sarah Sharp
2012-05-11 19:14 ` Alan Stern
2012-05-11 20:21 ` Sarah Sharp
2012-05-11 20:36 ` Alan Stern
2012-05-11 23:59 ` Sarah Sharp
2012-05-12 0:17 ` Greg KH
2012-05-12 13:54 ` Alan Stern
2012-05-14 23:21 ` Sarah Sharp
2012-05-15 14:31 ` Lan Tianyu
[not found] ` <4FB268CA.9060304-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2012-05-15 15:18 ` Greg KH
2012-05-15 20:00 ` Sarah Sharp
2012-05-16 6:26 ` Lan Tianyu
2012-05-16 14:36 ` Alan Stern
2012-05-16 14:39 ` Greg KH
2012-05-16 14:54 ` Lan Tianyu
2012-05-16 15:08 ` Greg KH
2012-05-16 15:32 ` Lan Tianyu
[not found] ` <20120516150846.GB3293-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2012-05-16 15:57 ` Sarah Sharp
2012-05-16 15:12 ` Alan Stern
[not found] ` <20120516143958.GA612-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2012-05-17 11:42 ` Sergei Shtylyov
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