When I connect my android phone in fastboot mode and enter fastboot devices ,I get no output at terminal ,but when I enter fastboot -i 0x1ebf devices I get an output.I need -i option with every other fastboot commands too. Why ???
fastboot utility had an internal whitelist for USB vendor IDs, which included only some major Android device vendors:
0x0451 Texas Instruments 0x0502 Acer 0x05c6 Qualcomm 0x0955 Nvidia 0x0b05 Asus 0x0bb4 HTC 0x0fce Sony Ericsson 0x18d1 Google 0x22b8 Motorola 0x2314 INQ Mobile 0x413c DELL 0x8087 Intel
In the AOSP commit from 2015-08-10 this USB vendor ID whitelist was removed, therefore new
fastboot versions should work with all Android devices without needing the
-i 0xXXXX option (now the option just limits the selection in case multiple Android devices from different vendors are connected). However, the most current platform-tools release (23) at the time of writing this answer does not yet have this commit included, therefore you will need to keep using the
-i 0xXXXX option for some time.