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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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  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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