# cat /sys/kernel/debug/mmc3/ios

clock:          50000000 Hz

actual clock:   49500000 Hz

vdd:            21 (3.3 ~ 3.4 V)

bus mode:       2 (push-pull)

chip select:    0 (don't care)

power mode:     2 (on)

bus width:      2 (4 bits)

timing spec:    2 (sd high-speed)

signal voltage: 0 (3.30 V)

Read속도 :  (524 MB) copied, 0.878213 s, 597 MB/s

Write 속도 :  (419 MB) copied, 32.4127 s, 12.9 MB/s

dd if=/dev/zero of=/dev/mmcblk3p1 bs=4096 count=100K

102400+0 records in

102400+0 records out

419430400 bytes (419 MB) copied, 32.4127 s, 12.9 MB/s

root@imx6qsabresd:~# dd if=/dev/mmcblk3p1 of=/dev/zero bs=4096 count=100K

102400+0 records in

102400+0 records out

419430400 bytes (419 MB) copied, 0.690988 s, 607 MB/s

root@imx6qsabresd:~# dd if=/dev/mmcblk3p1 of=/dev/zero bs=4096 count=200K

128000+0 records in

128000+0 records out

524288000 bytes (524 MB) copied, 0.878213 s, 597 MB/s