isochronous support broken?

matthieu castet castet.matthieu at
Sun Jan 8 16:48:55 EST 2006

Hi Duncan,

Duncan Sands wrote:
> Hi Alistair,

> -ENOSPC         This request would overcommit the usb bandwidth reserved
>                 for periodic transfers (interrupt, isochronous).
> Interesting.  What kernel version is this (I noticed some bandwidth changes
> going into 2.6.15)?  Do you have other iso devices connected at the same time?
For me (eagle) with the default configuration of usbatm I use 121% of 
the bandwidht [1]

I need to reduce the number of iso packet via module parameter.


T:  Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12  MxCh= 2
B:  Alloc=1091/900 us (121%), #Int=  1, #Iso=  4
D:  Ver= 1.10 Cls=09(hub  ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=0000 ProdID=0000 Rev= 2.06
S:  Manufacturer=Linux 2.6.15 uhci_hcd
S:  Product=UHCI Host Controller
S:  SerialNumber=0000:00:10.0
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  0mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   2 Ivl=255ms

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