On Mon, 4 Nov 2013, Moritz Fischer wrote: > Hi guys, > > This is my first post to this list, so let me quickly introduce myself. > I'm a software engineer for Ettus Research (National Instruments). > > One of our new products [1] is a USB 3.0 (using Cypress FX3) based SDR > that currently ships > with a libusb based open source driver integrated in our open source > UHD userland driver. > > Our device comes with ADC/DACs that need high throughput streaming > from and to the host. > We're using bulk transfers to send data to a Spartan 6 FPGA in the device. > > As the CPU usage is quite high and the throughput using libusb is not > as high as we > expect we're currently looking into developing a kernel driver. > Profiling showed we're spending quite some time in the kernel when > using libusb. A patch was proposed in the last couple of months to reduce kernel overhead for transfers using libusb: http://marc.info/?l=linux-usb&m=138046339714340&w=2 The patch would need to be finished and all the relevant comments addressed, and libusb might need some changes to match. Still, this seems like it would be easier than writing your own kernel driver. > I've started grepping around the tree for an example to steal from and > stumbled upon the > drivers/usb/usb-skeleton.c file. > > Can I base a high throughput (streaming) USB 3.0 driver off of this or > is this not a good starting point to look at? What do you think you could add to usb-skeleton that isn't already present in usbfs/libusb? They do support streaming. > Are there other device drivers to look at that might give me some > insight into how to deal with super speed devices using bulk > transfers? If there is nothing to look at (yet) I'm happy to work on > this and contribute our solution back. There are no drivers specifically meant for SuperSpeed bulk transfers, except for uas. And that is quite different from what you're talking about, because it uses multiple streams (which is not the same thing as streaming, despite the similarity in the names). Alan Stern -- 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
