On Thu, 19 Jul 2012, Markus wrote: > On Wed, 18 16:58 , Peter Stuge wrote: > > > > Why do you want to do this again? You mentioned bus bandwidth. > > How would you like to use the bandwidth knowledge? > > Short answer: > > Because it helps to sort out data-rate problems that might occur > due to several high-bandwidth devices sharing a single bus for > USB 3.0. > > Long answer: > > In the not-too-distant future some devices will appear on the > market that will use the bandwidth that USB 3.0 provides. In > fact, industrial cameras only adapt USB 3.0 because of its > bandwidth superiority to Gigabit Ethernet. But the 400 MB/s will > also be interesting for hard disks and the like. > > Now imagine you wonder why your device only transmits data with > an unsatisfying rate. The first thing I'd do is checking if the > device can use the full bus bandwidth, i.e. if there are some > other devices on the same bus. > > The only way to get a clue about this is looking how many > devices are attached to a certain host controller. > > In case of a PCIe card, this is easy because I can distinguish > the ports belonging to a card. This is difficult at least if the > HC chip is onboard and ports from different HCs are placed on the > rear of a PC. Let alone a 19" device, where eyeballing might not > be possible at all in the short term. > > However, this would be more easily solved in software, if there > is a way to retrieve which device are on a common bus.
Earlier you wrote: > > Right now, I can reliably tell which devices share a common bus. So what's the problem? > It will also be helpful to know the manufacturer and model of a > HC in those cases. I agree. However, host controllers aren't USB devices. That is, they don't attach to a USB bus; they attach to some other sort of bus, such as PCI. Hence to learn the manufacturer and model of a host controller you would need to use a library or API suitable for that other sort of bus. There's no reason to expect libusb or libusbx to provide the information. Alan Stern ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ libusbx-devel mailing list libusbx-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libusbx-devel
