On Sun, Sep 29, 2013 at 5:22 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Sun, Sep 29, 2013 at 01:51:58PM +0200, Markus Rechberger wrote: >> I searched with google, obviously no one is using USBFS/userspace USB >> drivers that intensive as we do because (streaming 6mb for DVB or 20mb >> for Analog over days) the only bug reports that come up are related to >> our devices and point to our forum. > > Not true at all, I know of at least one company, and odds are there are > many others, that have been doing this type of thing since the 2.2 > kernel days, in their embedded systems for the military. > military and high speed transfer? Must be some party losing the war because of stalled transfers ha ha. Maybe that's how and why Iran caught the US drone back then. (joking). I think back then the isochronous transfer buffers were also quite small, and we lost some data packets back then. It worked but the driver did skip some frames with systems <2.6.32 systems once some other load came up on the system. > They do it all in userspace, for vision systems, using usbfs. > > So you aren't alone at all, just the only ones with reported problems :) > yes however there are problems as indicated. They rarely happen with normal PC systems (if at all). One problem (latency issue due too small buffers) is happening because of the particular chipset on those embedded systems, SG transfer behavior is unknown since there's no uptodate kernel is available on that system. I'd prefer to support both mechanisms before forcing the SG behavior on everything. Markus -- 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
