system clock slowing down due to PN7150 on custom imx6ul board

[pratyushtomar]

We have a custom board based on imx6ul evk except that we are using lpdd2 ram. The problem is that if we use ondemand or conservative mode the system clock becomes very slow. For every 10 seconds update the board system clock updates only 3 sec. But as soon as we change board mode to performance mode the system clock works fine.

After testing we found that it's due PN7150 settings in dts file. After removing PN7150 settings from dts file we found that system clock works fine in conservative or ondemand mode. Now the question is why PN7150 is causing system clock of board to slow down even though  when we are not using PN7150. We used following settings for PN7150 in our dts file.

pn547: pn547@28 {
compatible = "nxp,pn547";
reg = <0x28>;
clock-frequency = <400000>;
interrupt-parent = <&gpio1>;
interrupt-gpios = <&gpio1 30 0>;
enable-gpios = <&gpio1 25 0>;
};

MX6UL_PAD_UART3_RX_DATA__GPIO1_IO25 0x3008 /*NFC ENABLE */
MX6UL_PAD_UART5_TX_DATA__GPIO1_IO30 0x0 /*NFC IRQ */

[gusarambula]

Hello Pratyush Tomar,

It's great that you managed to catch this. Let me investigate if someone has found a similar behavior. From what I understand you are not using this module so it's not physically connected to the board and just the presence of the device tree configuration for the PN7150 seems to be the root cause, correct?

Regards,

[pratyushtomar]

Hello we did further testing and found out that the issue is not due to PN7150. It's because of USB OTG controller module of cpu remains not powered if usb cable is unplugged. If we plugin the cable the clock works fine even if we are not using power from usb to run our board