"Very rarely detected" means the error happens frequently and it only works sometimes. The error is this one:
[ 4.670203][ T34] mmc_host mmc2: card is non-removable.
[ 4.703241][ T34] mmc_host mmc2: Bus speed (slot 0) = 400000Hz (slot req 400000Hz, actual 400000HZ div = 0)
[ 4.757624][ T44] mmc_host mmc2: Bus speed (slot 0) = 50000000Hz (slot req 50000000Hz, actual 50000000HZ div = 0)
[ 4.777618][ T44] mmc2: error -84 whilst initialising SDIO card
[ 4.811293][ T44] mmc_host mmc2: Bus speed (slot 0) = 300000Hz (slot req 300000Hz, actual 300000HZ div = 0)
[ 4.893354][ T44] mmc_host mmc2: Bus speed (slot 0) = 50000000Hz (slot req 50000000Hz, actual 50000000HZ div = 0)
[ 4.903224][ T44] mmc2: error -84 whilst initialising SDIO card
[ 4.936591][ T44] mmc_host mmc2: Bus speed (slot 0) = 200000Hz (slot req 200000Hz, actual 200000HZ div = 0)
[ 4.977762][ T44] mmc_host mmc2: Bus speed (slot 0) = 50000000Hz (slot req 50000000Hz, actual 50000000HZ div = 0)
[ 4.986768][ T44] mmc2: error -84 whilst initialising SDIO card
[ 5.014797][ T44] mmc_host mmc2: Bus speed (slot 0) = 187500Hz (slot req 187500Hz, actual 187500HZ div = 0)
[ 5.337342][ T44] mmc_host mmc2: Bus speed (slot 0) = 50000000Hz (slot req 50000000Hz, actual 50000000HZ div = 0)
[ 5.350427][ T44] mmc2: error -84 whilst initialising SDIO card
[ 5.433537][ T44] mmc2: Failed to initialize a non-removable card
I compiled Gentoo, but I didn't use Gentoo kernel. I used the mainline, official, torvalds' kernel from github.
