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imx6ull define sd card speed/clock frequency

Question asked by Alexander Lampret on Jun 19, 2017
Latest reply on Jun 22, 2017 by igorpadykov



I've created a custom imx6ull board and therefore copied dts from imx6ul-14x14 evk board.

In this dts file, there are 3 pinctrl for "default", 100MHz and 200MHz.


Current result of cat /sys/kernel/debug/mmc0/ios is:

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)

driver type: 0 (driver type B)


How is it possible to increase clock and speed? Which settings have to be changed?

Currently, read from sd card is quite slow.