On Mon, May 15, 2017 at 02:47:48PM +0200, Guido.Kiener@xxxxxxxxxxxxxxxxx wrote: > Hi all, > > Some members of the IVI Foundation www.ivifoundation.org have founded a > working group “VISA for Linux” that defines common rules, header files, > and shared libraries for Linux to implement the specification of "VPP-4.3: > The VISA Library" (see > http://ivifoundation.org/specifications/default.aspx). > > Moreover the interoperability of the USBTMC protocol is one of our > requirements. We know that you have already improved the Linux USBTMC > driver (linux/drivers/usb/class/usbtmc.c) that can communicate with T&M > instruments. However we are not sure whether this driver already includes > all features that we need for our instruments and for the VISA API. > Therefore we ask you to give us some recommendations or replies to our > questions: > > 1. "Libusb" versus usbtmc driver: Using "libusb" seems to be a good > alternative for all Linux platforms and is the right fallback solution > until future versions of the USBTMC includes all required features. It also works on all other operating systems as well, Windows included, so you might find this very useful for everyone. > Do you think we should extend the USBTMC driver with our required > features (e.g. vendor specific IO, SRQ handling, asynchronous IO, raw > USB IO, timeout)? Sure, send patches on, we will be glad to review and evaluate them. > Or do you think we shall keep the USBTMC driver in the current state? > How long would it take to get changes into the Linux kernel? It depends on what the patches look like :) Take a look at the kernel files, Documenatation/development_process/ for how the kernel is developed. If you send us a bugfix, we can get that merged within a week or so. If it's a new feature or driver, that has to wait until the next merge window, which happens ever 2 1/2 months. But don't worry too much about this, send your changes on and we can review them and go from there. > 2. As we have looked at the Linux driver, we’ve noticed that performance > of the usbtmc_read() function doesn’t keep up with our fastest > instruments. Do you have any suggestions on how to improve the read > performance? Where exactly are things not going fast enough? Have you found any specific bottlenecks? How fast are you needing to go? What type of interface do you expect userspace to have to handle high rates of data? > 3. Do you have any plans to modify/evolve the USBTMC driver moving > forward? We review any patches that people submit, just like with any other kernel driver or subsystem. Nothing different about this one tiny driver :) > 4. Do you know of any other differences between the Linux USBTMC driver > and the Windows USBTMC driver? Most people here have never run windows, so you are asking the wrong group :) Have you evaluated both and found any differences? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
