Date: Wed, 15 Jun 2011 09:33:14 +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: <20110615093314.GA83570@freebsd.org> In-Reply-To: <201106142231.31782.hselasky@c2i.net> References: <mailpost.1307994762.7302932.44894.mailing.freebsd.usb@FreeBSD.cs.nctu.edu.tw> <201106141440.25693.hselasky@c2i.net> <4DF75978.7010909@FreeBSD.org> <201106142231.31782.hselasky@c2i.net>
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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: 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? 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. 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. cheers. alex > > --HPS -- a13xhelp
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