SD2_CLK at 33MHz (eMMC clock) BUT set to 50Mhz in dtsi file IMX6ULL

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SD2_CLK at 33MHz (eMMC clock) BUT set to 50Mhz in dtsi file IMX6ULL

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guillaume_costa
Contributor I

Hi,

On IMX6ULL I have set the clock for eMMC to 50Mhz but when I list the clocks in the linux kernel. It's written : (I can measure 33 Mhz also with the scope).

cat /sys/kernel/debug/mmc1/ios
clock: 52000000 Hz
actual clock: 33000000 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: 8 (mmc DDR52)
signal voltage: 0 (3.30 V)
driver type: 0 (driver type B)

 

Below my dtsi part with the usdhc2 node :

&usdhc2 {
pinctrl-names = "default";
pinctrl-0 = <&PINS_USDHC2>;
bus-width = <8>;
no-1-8-v;
broken-cd;
keep-power-in-suspend;
wakeup-source;
status = "okay";
};

Why the clock is blocked to 33Mhz ? It could produce looses in terms of performances.

Guillaume

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5 Replies

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Hansen110
Contributor I

use the 5.4.70 and i was having several issues if you could help out than it will be great keep posting suggestions. 

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1,088 Views
guillaume_costa
Contributor I

We use the 5.4.70 .

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1,084 Views
igorpadykov
NXP TechSupport
NXP TechSupport

could you provide full logs, uboot+linux.

 

Best regards
igor

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1,074 Views
guillaume_costa
Contributor I

Hi Igor,

 

Here you can find the full logs of u-boot 2020.04 + kernel (5.2.70)

 

On mmc0 the frequency is correct ( uSD)

 

On mmc1 (usdhc2) the frequency is 33Mhz instead of 52Mhz as you can see below :

 

root@val900:~# cat /sys/kernel/debug/mmc1/ios
clock: 52000000 Hz
actual clock: 33000000 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: 8 (mmc DDR52)
signal voltage: 0 (3.30 V)
driver type: 0 (driver type B)

 

 

Best regards,

 

Guillaume

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1,100 Views
igorpadykov
NXP TechSupport
NXP TechSupport

Hi Guillaume

 

what bsp used in the case, may be recommended to try with latest nxp releases from

source.codeaurora.org/external/imx/linux-imx repository
https://source.codeaurora.org/external/imx/linux-imx/tree/?h=lf-5.10.y

Documentation

https://www.nxp.com/design/software/embedded-software/i-mx-software/embedded-linux-for-i-mx-applicat...

 

Best regards
igor

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