Date: Tue, 06 Jun 2006 01:48:25 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: jhs@berklix.org Cc: garyj@jennejohn.org, freebsd-usb@freebsd.org Subject: Re: usbdevs "self powered" is misleading Message-ID: <20060606.014825.232930089.imp@bsdimp.com> In-Reply-To: <200606051201.k55C1NHd087760@fire.jhs.private> References: <200606051201.k55C1NHd087760@fire.jhs.private>
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In message: <200606051201.k55C1NHd087760@fire.jhs.private>
"Julian Stacey" <jhs@berklix.org> writes:
: "self powered" is reported by 6.1-RELEASE usbdevs for my small external disc.
: It seems a misnomer & should at most be "Can be self powered" ?
: The disc housing has a socket to apply power, but was not plugged
: in. (I don't even have a power supply for it). Disc was cabled
: direct to laptop, not through a hub, & showed:
: Controller /dev/usb1:
: addr 1: full speed, self powered, config 1, UHCI root hub(0x0000),
: Intel(0x0000), rev 1.00
: port 1 addr 2: full speed, self powered, config 1,
: USB 2.0 Storage Device(0x5621), vendor 0x0402(0x0402), rev 1.03
: When I added a USB-2 Hub (with hub power supply plugged in to 220V)"
: Controller /dev/usb1:
: addr 1: full speed, self powered, config 1, UHCI root hub(0x0000),
: Intel(0x0000), rev 1.00
: port 1 addr 2: full speed, self powered, config 1,
: USB2.0 Hub Cont(0x0058), NEC Corporation(0x0409), rev 1.00
: port 1 addr 5: full speed, self powered, config 1,
: USB 2.0 Storage Device(0x5621), vendor 0x0402(0x0402), rev 1.03
: Sometimes "self powered" seems correct though, as for eg:
: - a GPS with battery inside.
: - a USB2-IDE + 3.5" IDE disc + external 220V supply
: Comments ?
Self Powered just means that the device has told the hub it doesn't
need any power. These are standard attributes of the device which the
device reports. FreeBSD just reports these to the user.
Warner
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