I applied manually the gentoo patches and I discovered that the patch "2910_TVP5150-Fix-build-issue-by-selecting-REGMAP-I2C.patch" resulted in fuzz 2 at kernel 5.9. Upon investigation I found that it is no longer needed since kernel 5.7. It was fixed in upstream: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/media/i2c/Kconfig?h=v5.7 The gentoo patches for linux 5.7 and 5.8 are correct and don't carry the patch, but it returned with 5.9 and 5.10.
Thanks for reporting
commit aa954dee464f3d5a77e694c3a34da5ffba988eea (HEAD -> 5.9, origin/5.9) Author: Mike Pagano <mpagano@gentoo.org> Date: Sun Dec 13 11:10:02 2020 -0500 Removed redundant patch. Thanks to leandrolnh for reporting Removed: 2910_TVP5150-Fix-build-issue-by-selecting-REGMAP-I2C.patch Closes: https://bugs.gentoo.org/759646 Signed-off-by: Mike Pagano <mpagano@gentoo.org>