On Thu, 14 Feb 2008, vichy wrote: > Dear all: > I list the initial sequences that I observed from source code. > If I get something wrong, please let me know. > > Suppose I get 3 devices connected to a host, A, B and C. > A plugs in. > We use QH with device-address = 0, ep = 0 to get A's device descriptor. > Set A's device address to 1.
Okay. > B plugs in. > We use QH with device-address = 0, ep = 0 to get B's device descriptor. > Set A's device address to 2. No. Instead, set B's device address to 2. > C plugs in. > We use QH with device-address = 0, ep = 0 to get C's device descriptor. > Set A's device address to 2. No. Instead, set C's device address to 3. > So Qh with device-address = 0, ep = 0 is always the default and least QH to > get every device's device descriptor, right? I don't understand your question. Resetting a device sets its address to 0. Each device is automatically reset when you plug it in; that's why we need to use a QH with device address = 0 to read the device descriptor. But once the device descriptor (more precisely, the maximum packet size for endpoint 0, which is stored in the device descriptor) is known, the device is assigned a unique address. Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
