Date: Mon, 28 May 2007 08:43:45 +0200 From: Hans Petter Selasky <hselasky@c2i.net> To: "M. Warner Losh" <imp@bsdimp.com> Cc: freebsd-usb@freebsd.org Subject: Re: 31st address line sometimes not used on EHCI/UHCI/OHCI Message-ID: <200705280843.45808.hselasky@c2i.net> In-Reply-To: <20070527.145412.-1597331197.imp@bsdimp.com> References: <200705272235.46048.hselasky@c2i.net> <20070527.145412.-1597331197.imp@bsdimp.com>
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On Sunday 27 May 2007 22:54, M. Warner Losh wrote: > In message: <200705272235.46048.hselasky@c2i.net> > > Hans Petter Selasky <hselasky@c2i.net> writes: > : I've got some reports back that some USB host controllers do not support > : transferring memory from a location higher than 2GB. > : > : What should we do about this? > : > : Should we limit all USB DMA allocations to the lower 2GB of the memory? > > busdma should be managing this behind the scenes. You shouldn't care, > as the problematical usb controllers, if any, can do the bouncing as > required. We need to get the hierarchical bus tagging stuff more > fully integrated, then we'd get this for free. Yes, I just changed the lowaddr when I allocated the tag, and that did the trick! > > Of course, you'd have to stop using contigmalloc to allocate all the > memory for usb. That won't work on some of the embedded platforms we > have, for example, because memory on them isn't as fungible as it is > on i386 and amd64. My new USB stack has been using "bus_dmamem" for quite a while. --HPS
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