[U-Boot] "Reset" values for clksel_con registers in clk_rk3399.c:rkclk_init()

[Dr. Philipp Tomsich]

Kever,

I came across an odd question in clk_rk3399.c while implementing the reparenting
(for assigned-clock-parents) that I today discussed with David Wu… looks like the
following code is supposed to restore the reset values to 3 registers, but both the
NDA-version of the TRM and the public version of the TRM list different (consistent
between the two TRM versions) values.

The code in question is:
        /*                                                                                                                                                         
         * some cru registers changed by bootrom, we'd better reset them to                                                                                        
         * reset/default values described in TRM to avoid confusion in kernel.                                                                                     
         * Please consider these three lines as a fix of bootrom bug.                                                                                              
         */
        rk_clrsetreg(&cru->clksel_con[12], 0xffff, 0x4101);
        rk_clrsetreg(&cru->clksel_con[19], 0xffff, 0x033f);
        rk_clrsetreg(&cru->clksel_con[56], 0x0003, 0x0003);

However, my manual states that the default values are:
	CLKSEL_CON12		0x100
	CLKSEL_CON19		0x100
	CLKSEL_CON56		0x320

This came in with commit 9f636a24 ("rockchip: rk3399: init CPU clock when rkclk_init()”).

This popped up on my radar, as I was wondering why GbE had been working so far
for us, even though we never had any reparenting code for the RK3399.

Do you know why our init code is setting these values and why this doesn’t match
the comment? I also tried to see if the register-numbers were wrong and the writes
went to the wrong registers, but I couldn’t find any register in the CLKSEL_CON block
that had 0x4101 or 0x33f as a default/reset value.

Thanks,
Philipp.