foolish problem with installer: can't load firmware

[<loushanguan2015@sina.com>]

i start bullseye installer from usb stick

it tells me to insert usb stick containing firmware

i fail in this step many times

after many failures, i learn that firmware shall be in vfat partition, not ext4

and i have to remove installer stick so that installer can read firmware stick

though i have many usb ports

after firmware are successfully loaded and after some steps

installer complains it can't read installer stick

no matter how quickly i insert installer stick after loading firmware

is there some usb command that can help after i remove and insert installer stick?

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