Messages in this thread | | | Date | Thu, 24 Feb 2005 22:38:53 +0100 | From | Lukas Hejtmanek <> | Subject | Re: USB 2.0 Mass storage device |
| |
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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |