Re: USB 2.0 Mass storage device

[Lukas Hejtmanek <xhejtman@mail.muni.cz>]

On Thu, Feb 24, 2005 at 01:15:12PM -0800, Greg KH wrote:
> And if you look at the raw descriptors, which is what is displayed in
> /proc/bus/usb/devices in human readable form, the device itself tells
> the computer what speed it supports.  The host never tells the device
> what speed to run at.

I do not think so.

This is another device (Card reader) supporting USB 2.0. 

In this case I used only uhci_hcd driver and it reports speed 12.

T:  Bus=04 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  3 Spd=12  MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=05dc ProdID=b018 Rev= 1.28
S:  Manufacturer=Lexar Media
S:  Product=Multi-Card Reader
S:  SerialNumber=0000246504
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=500mA
I:  If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
E:  Ad=81(I) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms

In this case I used both ehci_hcd and uhci_hcd drivers (ehci detected device)
and it reports speed 480. 

T:  Bus=01 Lev=01 Prnt=01 Port=04 Cnt=01 Dev#=  2 Spd=480 MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=05dc ProdID=b018 Rev= 1.28
S:  Manufacturer=Lexar Media
S:  Product=Multi-Card Reader
S:  SerialNumber=0000246504
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=500mA
I:  If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms

So for me it looks like it reports speed according to USB driver or negotiated
speed.

-- 
Lukáš Hejtmánek