PCIE-HUB chip not being detected on boot occasionally

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
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After a few days of survey, I found the following POST.

After changing max-speed from (4 - Gen-4) to (2 - Gen-2) like the above POST,
the problem that the DownPort destination device is not recognized was resolved.
The phenomenon of the error in of_irq_parse_pci() also does not occur.

	pcie@141a0000 {
		status = "okay";

		vddio-pex-ctl-supply = <&p3668_spmic_sd3>;
		nvidia,disable-aspm-states = <0xf>;
		nvidia,enable-power-down;
-		nvidia,max-speed = <4>;
+		nvidia,max-speed = <2>;
...

Since the maximum speed supported by the PCIE-HUB CHIP(PI7C9X2G608GP) is Gen-2,
and our custom board always connects devices via the PCIE-HUB CHIP(PI7C9X2G608GP),
we will fix this by setting max-speed=2.

In the JetsonNano environment, PCIE port supports Gen-2 speed by default,
which may have prevented this problem.

However, I think that there may be a bug in the speed negotiation process
from max-speed=4 in Jetson XavierNX.

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