Stefan, On Fri, Jan 29, 2016 at 7:28 AM, Stefan Wahren <stefan.wahren@xxxxxxxx> wrote: > Hi Doug, > > Am 27.01.2016 um 21:43 schrieb Doug Anderson: >> Stefan, >> >> On Wed, Jan 27, 2016 at 12:36 PM, Stefan Wahren <stefan.wahren@xxxxxxxx> wrote: >>> i can only give you feedback from a user perspective. My keyboard and C-Media >>> USB Audio still works as expected. >> OK, thanks! So you had no problems before my patches and you still >> have no problems after my patches. ...but your USB setup is fairly >> simple, at least. Your testing is still valuable (thank you thank you >> thank you), I just wanted to check. :) > > if you need a result from a different USB setup in combination with your > Patch V6 please describe. > > But i don't have a USB analyzer at home ;-) Many (but not all) of my bugfixes are around dealing with with split transactions. That happens when you've got a high speed hub hooked up to the port and then you attach a bunch of low speed / full speed devices. Things were even buggier if you attached a "single tt" hub. A "single tt" hub means that all low speed / full speed devices on the hub are treated as being on a single full speed hub. Said another way, if you have a single tt hub then all of the low speed / full speed devices attached to that hub need to share 12 MB/s of bandwidth. If you have a multi tt hub then each of the low speed / full speed devices attached to the hub have their own 12 MB/s of bandwidth. Most hubs I've randomly obtained are single tt. In any case, before my patches: * If you have a USB Audio device that is FULL SPEED (not high speed) plus a mouse or keyboard, playing audio will tend to cause problems with the mouse / keyboard. * Attaching multiple keyboards / mice to a hub would tend to cause dropped keys on the keyboards / slow mice. Things were worse with fancier keyboards in general. You didn't need to type things on all keyboards at once, just have them attached. * In general the more stuff you pile onto a hub the more problems. My stressful USB test case was to get a USB webcam + USB audio + a few mice / keyboards. That ought to improve significantly with my patches, though I'm not 100% sure that the Raspberry Pi will really be able to keep up with all that. The USB webcam might be especially stressful due to some craziness with uncached memory and URB completion happening with interrupts disabled (even after forking things off to a tasklet). I can go into this more if someone is interested but there's a bit of details in <https://chromium-review.googlesource.com/#/c/321980/> and <https://chromium-review.googlesource.com/#/c/321932/>. If you happen to have a FULL SPEED (USB 1.1) hub it would also be interesting to plug that into your Pi directly and then plug a few things into it. One of my patches addresses a problem related to that. Of course, it's pretty hard to track down a full speed hub these days (I've got a box full of old peripherals in my closet). -- 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
