Hi,
Why the clock and actual clock is different in mmc for imx8qxp?
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# cat /sys/kernel/debug/mmc0/ios
clock: 200000000 Hz
actual clock: 166666666 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: 3 (8 bits)
timing spec: 10 (mmc HS400)
signal voltage: 1 (1.80 V)
driver type: 0 (driver type B)
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Is it possible to increase actual_clock and will it help in increasing the speed of mmc?
Thanks in Advance,
Regards,
Wasim
Hi Wasim
>Why the clock and actual clock is different in mmc for imx8qxp?
this is because linux clock driver divides and rounds plls frequency to most appropriate
value. Description linux common clk framework
https://www.kernel.org/doc/Documentation/clk.txt
>Is it possible to increase actual_clock and will it help in increasing the speed of mmc?
in general one can try to reprogram parent pll, however linux emmc driver selects speed
automatically based on emmc CSD register which carries the device specific information
like data transfer speed.
Best regards
igor
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