After some more researches, I discovered the source command I didn’t know. So I had a look in /usr/lib/u-boot/platform_install.sh, found the write_uboot_platform_mtd function and removed the -p option from the line containing flashcp, then it seemed to work this time.
I would be glad, however, if someone could tell me if this is really fine, or if something supposed to be handled by this -p option may be missing… it doesn’t seem to be the case to me, but a more expert opinion would be appreciated.
Thanks