Date: Wed, 15 Jun 2011 10:00:23 +0000 From: Alexander Best <arundel@freebsd.org> To: Hans Petter Selasky <hselasky@c2i.net> Cc: Alexander Motin <mav@freebsd.org>, freebsd-usb@freebsd.org, Joel Dahl <joel@freebsd.org> Subject: Re: USB 3.0 support by default? Message-ID: <20110615100023.GA87337@freebsd.org> In-Reply-To: <201106151141.47408.hselasky@c2i.net> References: <mailpost.1307994762.7302932.44894.mailing.freebsd.usb@FreeBSD.cs.nctu.edu.tw> <201106142231.31782.hselasky@c2i.net> <20110615093314.GA83570@freebsd.org> <201106151141.47408.hselasky@c2i.net>
index | next in thread | previous in thread | raw e-mail
On Wed Jun 15 11, Hans Petter Selasky wrote: > On Wednesday 15 June 2011 11:33:14 Alexander Best wrote: > > On Tue Jun 14 11, Hans Petter Selasky wrote: > > > On Tuesday 14 June 2011 14:52:08 Alexander Motin wrote: > > > > Hans Petter Selasky wrote: > > > Done: > > > > > > http://svn.freebsd.org/changeset/base/223098 > > > > btw., if i might ask a technical and probably naive question: > > Hi, > > > > > does USB 3.0 feature *full* backward compatibility? that is supporting usb > > 1.x and usb 2.0 devices without the need for enabling those legacy > > controllers? > > Yes, XHCI is a replacement for EHCI and OHCI and UHCI. It speaks multiple > protocols. thanks a lot for clearing things up. :) > > > > > so will xhci give me all the backward compatibility or do i have to also > > enable a combination of ohci/uhci/ehci? with usb 2.0 there was no usb 1.x > > support unless ohci/uhci was also enabled. > > > > i read that the xhci controllers don't depend on CPU and I/O availability > > as much as the old controllers. doing CPU intensive tasks shouldn't have > > such a massive effect on USB transfer times, compared to usb 1.x and 2.0. > > that's why i'd like to completely get rid of the need for ohci/uhci/ehci > > in my kernel config. > > Due to certain commercial OS'es which haven't got XHCI support, hardware > manufacturers have come up with creative solutions which involves custom bits > to switch ports to and from XHCI/EHCI. > > > i'd really like to see some transfer time statistics with CPU being close > > to 100% idle and with CPU being hammered close to 100% with usb 3.0. i > > think i did such a test a while ago for usb 2.0 and transfer rates dropped > > quite significantly. > > --HPS -- a13xhome | help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20110615100023.GA87337>