Hello, some questions regarding the communication while probing.
I am using Linux kernel 2.4.18. I write some device drivers for USB devices (embedded system, not host pc!). I connect this USB device to a host pc running Linux kernel 2.4.18 either. I use a tiny driver evolved from Greg's USB skeleton driver to see the descriptors values and to get some data exchange. 1. ----------- GetDescriptor-Request Stringdescriptor: I noticed that the indices for string descriptors seem to be static in value. Example: In the devices driver did some defines like: #define STR_INTERFACE_DESCRIPTOR 0x05 #define STR_SERIALNUM_DESCRIPTOR 0x03 In the desriptor tables these numbers are set correct, still when the Linux host does enumeration and does a request for the string of the serialnumber the interface string is is written into dev->SerialNumber on the host side. If I change the values for these defines, this assignment is done correctly. Shouldn't the indices be of any byte wide value? Shouldn't the host pc "scan" these indices, as they are sent e.g. in the configuration descriptor? Why does it seem, that I have to use a certain numbering plan for indices? 2. ------------ I adopted to: #define STR_INTERFACE_DESCRIPTOR 0x03 #define STR_SERIALNUM_DESCRIPTOR 0x05 Now I do enumeration again. When it first comes to the request of GetDescriptor Serialnumber, .wValue is set correctly to 0x0305, accessing device number 3, indexing string number 5. But right after that I get another setup packet GetDescriptor Serialnumber with .wValue = 0x03F5. Since on the USB devices side I interpret low byte of .wValue as string index, this leads to an unknown index. As far as I read USB spec. the whole LSB contains the string index, not just the very lowest nibble, or am I wrong? So were does the "F" nibble comes from? Connecting the same device to a Windows 2000 system and monitoring data flow with an USB analyzer I don't see both of the effect mentioned above. BTW: Is there any developer out there, using Philips ISP1181? I got one tiny question someone else might be able to answer... Thank You for any reply. Siegfried. ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
