SpeedTouch and ISO mode, stats, ADSL Max.

David Woodhouse dwmw2 at infradead.org
Tue Mar 21 08:30:21 EST 2006

On Tue, 2006-03-21 at 14:19 +0100, Duncan Sands wrote:
> It is working, in the sense that it doesn't crash and it happily sends
> and receives packets.  But it's slow - slower than bulk!  In my tests I
> could get only a bit less than 4 Mbaud with bulk, and a bit less than
> that with iso.  However no-one else has yet been able to confirm similar
> speeds, so for all I know it might be an issue with my ISP.  But most
> likely there is a bottleneck in the driver.  I've been meaning to look
> into this for ages, but didn't have the time.

Alistair Strachan did report the same thing in January, archived at

He wrote "My bandwidth is still locked to just under 500KB/s (4MBits).
So either a) isoc isn't working or b) you need to do more than just
switch from bulk to isoc to get 8Mbits from this device. The Windows
workaround does not suggest this, but I suppose it is impossible to

"If it's a useful datapoint, I used to get sporadic errors and the USB
LED would flash RED if the bandwidth was held close to 4Mbit for a long
period of time. This no longer seems to happen with isoc, suggesting the
bandwidth bottleneck has been lifted. However, I do not see the 6.6
megabits I've synced at."

You asked about the 'Windows workaround' and he replied with pointers to

Perhaps there's some initialisation sequence we need to do to let the
firmware know it can go faster than 4Mbit/s, rather than just switching
to ISO mode and assuming it'll notice?


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