Date: Mon, 6 Mar 2017 11:25:17 +0100 From: Hans Petter Selasky <hps@selasky.org> To: Markus Rechberger <mrechberger@gmail.com>, freebsd-multimedia@freebsd.org Subject: Re: What is wrong with FreeBSD and USB Support Message-ID: <89e2eac5-5b95-ab42-a0ae-2ccb0b7483af@selasky.org> In-Reply-To: <CA%2BO4pCK4%2B1rE5ft4Boy_3xPdCxK31UtTQ2BYpnBUn5jxZr%2Bz_g@mail.gmail.com> References: <CA%2BO4pCK4%2B1rE5ft4Boy_3xPdCxK31UtTQ2BYpnBUn5jxZr%2Bz_g@mail.gmail.com>
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On 03/06/17 06:19, Markus Rechberger wrote: > Hi, > > I have been trying to port a driver to freebsd for a day now and the > result is quite negative. > > So my feedback about libusb20 and the FreeBSD USB Kernel Stack: > > 1. the documentation is not clear how to set up asynchronous bulk > transfers (please explain the architecture of this API) > > 2. the errors returned by libusb20 (and probably from the kernel) are > not detailed enough (in certain cases I'm able to get libusb20 unknown > error, to my understanding every error should have some meaning). > > 3. the FreeBSD USB Stack messes around with the transfer itself > damaging the entire result (eg resulting in stalled USB bulk > transfers). > > 4. The FreeBSD data transfer implementation itself is a disaster, I'm > able to transfer data at a rate of 2 MB/sec, anything higher results > in a stalled usb transfer?! > > 5. USB Control messages are 100% slower than with other operating > systems (eg. it took 14 seconds to load a driver with FreeBSD while it > only takes 7 seconds on other systems). > > Since I have been using USB stacks with Linux, Mac and some other > systems I can say that FreeBSD has the most irritating implementation > of all. > > So finally I wonder what is wrong with FreeBSD's USB support? Hi, Can you share some code and/or USB traces from "usbdump" for the slow traffic pattern. I'm pretty sure this isn't a FreeBSD problem, but how you use the APIs in FreeBSD's USB stack improperly. Further, which version of FreeBSD is this? Last but not least, if you are not observing 100% CPU usage on a CPU core during testing, it is for sure not a problem with the USB stack and/or IOCTL APIs. --HPS
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