hayeswang <hayeswang@xxxxxxxxxxx> writes: > Bjørn Mork [mailto:bjorn@xxxxxxx] > [...] >> Sorry, but then this makes even less sense. The active USB >> configuration is user selectable and you should make any of >> them work if >> possible. Why can't the drivers figure out this at runtime? > > Excuse me. I have no idea about how to switch the configuration at > the runtime ,and how to change the default configuration when a > USB device is plugged. When a user select one of the configurations, > he/she would wish to fix the configuration number after rebooting or > after the dangle is unplugged and plugged again. For these reasons, > this is the simple way which I could think. Maybe I choose the wrong > method because I don't know how to satisfy the requests. May you > provide me the relative information? Then, I could replace the current > method. Thanks. I apologise if I misunderstood you. When you mentioned multiple configurations, then I assumed it was a device similar to this one (partial output from /sys/kernel/debug/usb/devices): T: Bus=03 Lev=01 Prnt=01 Port=03 Cnt=01 Dev#= 4 Spd=480 MxCh= 0 D: Ver= 2.00 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs= 2 P: Vendor=1199 ProdID=68a2 Rev= 0.06 S: Manufacturer=Sierra Wireless, Incorporated S: Product=MC7710 S: SerialNumber=358178040092316 C: #Ifs= 6 Cfg#= 1 Atr=e0 MxPwr= 0mA I: If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver= E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms I: If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver= E: Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms I: If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver= E: Ad=83(I) Atr=03(Int.) MxPS= 64 Ivl=2ms E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms I: If#= 8 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver= E: Ad=85(I) Atr=03(Int.) MxPS= 64 Ivl=2ms E: Ad=86(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms I: If#=19 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver= E: Ad=87(I) Atr=03(Int.) MxPS= 64 Ivl=2ms E: Ad=88(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms I: If#=20 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver= E: Ad=89(I) Atr=03(Int.) MxPS= 64 Ivl=2ms E: Ad=8a(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=06(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms C:* #Ifs= 2 Cfg#= 2 Atr=e0 MxPwr= 0mA A: FirstIf#=12 IfCount= 2 Cls=02(comm.) Sub=0e Prot=00 I:* If#=12 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=0e Prot=00 Driver=cdc_mbim E: Ad=81(I) Atr=03(Int.) MxPS= 64 Ivl=2ms I: If#=13 Alt= 0 #EPs= 0 Cls=0a(data ) Sub=00 Prot=02 Driver=cdc_mbim I:* If#=13 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=02 Driver=cdc_mbim E: Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms Here you can see 2 configurations, where cfg #2 is active using a class driver. This is what Linux will choose in this case because the first interface of cfg #1 is vendor specific. But an end user can change it by writing to the bConfigurationValue sysfs attribute: nemi:/tmp# echo 1 > /sys/bus/usb/devices/3-4/bConfigurationValue giving this result: T: Bus=03 Lev=01 Prnt=01 Port=03 Cnt=01 Dev#= 4 Spd=480 MxCh= 0 D: Ver= 2.00 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs= 2 P: Vendor=1199 ProdID=68a2 Rev= 0.06 S: Manufacturer=Sierra Wireless, Incorporated S: Product=MC7710 S: SerialNumber=358178040092316 C:* #Ifs= 6 Cfg#= 1 Atr=e0 MxPwr= 0mA I:* If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=qcserial E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms I:* If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=qcserial E: Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms I:* If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=qcserial E: Ad=83(I) Atr=03(Int.) MxPS= 64 Ivl=2ms E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms I:* If#= 8 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=qmi_wwan E: Ad=85(I) Atr=03(Int.) MxPS= 64 Ivl=2ms E: Ad=86(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms I:* If#=19 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=qmi_wwan E: Ad=87(I) Atr=03(Int.) MxPS= 64 Ivl=2ms E: Ad=88(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms I:* If#=20 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none) E: Ad=89(I) Atr=03(Int.) MxPS= 64 Ivl=2ms E: Ad=8a(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=06(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms C: #Ifs= 2 Cfg#= 2 Atr=e0 MxPwr= 0mA A: FirstIf#=12 IfCount= 2 Cls=02(comm.) Sub=0e Prot=00 I: If#=12 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=0e Prot=00 Driver= E: Ad=81(I) Atr=03(Int.) MxPS= 64 Ivl=2ms I: If#=13 Alt= 0 #EPs= 0 Cls=0a(data ) Sub=00 Prot=02 Driver= I: If#=13 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=02 Driver= E: Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms Exactly the same device, but now cfg #1 is active and a different set of drivers have bound to the interfaces. This is possible because none of the involved drivers disable the support for this device at build-time. Instead they use the available interface descriptors for matching and probing supported functions. End users will of course normally not go around writing stuff to sysfs attributes like this. Creating an udev rule to select a specific counfiguration when the device is plugged is more useful for normal usage. My point was that this sort of runtime configuration change should be possible, assuming my understanding of the device layout is correct. Which it isn't necessarily. I don't have any such device and I haven't seen any USB descriptor dump from one either. Bjørn -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
