quoted

"tegra114.dtsi" has the folloiwng "tsc" entry. So can we consider that
if dts has this entry, CNTFRQ is not set, which implies it's in secure
mode. kernel should set it up by itself? Otherwise, skip this setup
and use it. For example:

 	tsc {
 		compatible = "nvidia,tegra114-tsc";
 		reg = <0x700f0000 0x20000>;
+		setup-cntfrq;
 	};

Is this what you explained in the above?
At least, kernel can survive without bootloader/firmware support, ATM.

No. The DT should only describe the hardware, and not something that is
Linux specific.

Just use the "clock-frequency" attribute in the timer arch-timer node,
and get rid of this CNTFRQ setting. The driver already knows how to deal
with this situation if this attribute is set.

The frequency is probed at boottime by the kernel though. It will not
necessarily be the same for every board.

Cheers,

Peter.