Date: Mon, 28 May 2007 00:59:44 -0700 From: Julian Elischer <julian@elischer.org> To: Hans Petter Selasky <hselasky@c2i.net>, freebsd-usb@freebsd.org Subject: Re: 31st address line sometimes not used on EHCI/UHCI/OHCI Message-ID: <465A8BF0.6050808@elischer.org> In-Reply-To: <20070528075022.GZ4602@funkthat.com> References: <200705272235.46048.hselasky@c2i.net> <20070527215329.GY4602@funkthat.com> <200705280853.18551.hselasky@c2i.net> <20070528075022.GZ4602@funkthat.com>
next in thread | previous in thread | raw e-mail | index | archive | help
John-Mark Gurney wrote: > Hans Petter Selasky wrote this message on Mon, May 28, 2007 at 08:53 +0200: >> On Sunday 27 May 2007 23:53, John-Mark Gurney wrote: >>> Hans Petter Selasky wrote this message on Sun, May 27, 2007 at 22:35 +0200: >>>> 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? >>> No, a quirk table should be setup and pass the restriction to bus_dma >>> at tag initalization time when a broken controller is detected.. >> Yes, I can do that. But I am also thinking about a static quirk, like a sysctl >> you can set at boot time. > > The only issue w/ this is that it would also effect add in USB PCI cards > that aren't effected by the bug... Which means a sysctl would limit the > hardware to the lowest common denominator... > >> I hope that this is not a wide-spread problem. >> >> And I am not surprised that hardware manufacturers are not specification >> compliant, which really makes me wonder if they support a true 64-bit address >> bus on the EHCI controller at all. I would maybe cost too much money? And >> therefore we should just stick with 32-bit addressing on 32-bit platforms >> aswell. > > Don't forget we have PAE for i386... so restricting to 32bit addressing > for i386 would have an impact... > > As for it being an intermediate bus being the issue, I'd be surprised > as that would mean that pci bridge to the USB controller is seriously > broken... At least dealing w/ a intermediate bus is easier now that > was have bus_get_dma_tag... > I'd rather it were a screwed up MB than a screwed up chip :-)
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?465A8BF0.6050808>