PS2 Clock

[AKuHAK]

linux/arch/mips/ps2/time.c

Line 27 in de37b46

#define CPU_FREQ 294912000 /* CPU clock frequency (Hz) */

Just would like to mention where is it taken from. Maybe it can be useful to add actual calculations.

That strange value is actually derived from the sample rate of the DAC. Here's how it works:
- The audio DAC runs at 48000 Hz.
- The SPU2 runs 768 (0x300h) cycles for every sample output, or 48000 Hz x 768 = 36864000 Hz.
- The system clock runs at this speed of 36864000 Hz. The IOP and SPU2 are directly clocked from this speed.
- The EE is running 8 times faster than the system clock speed. 36864000 Hz x 8 = 294912000 Hz, or just about 294.9 MHz.

Credits to jrra.
So something like this

 #define CPU_FREQ		48000*768*8	/* CPU clock frequency (Hz) */ 

[frno7]

Findings like this is very good and helpful. :-) I’ll make comments in the code about it, thanks!