PLL_VCLK_CNTL
uint8 vclkCntl = Mach64_GetPLLReg(PLL_VCLK_CNTL);
Mach64_SetPLLReg(PLL_VCLK_CNTL, vclkCntl | PLL_VCLK_RESET);
Mach64_SetPLLReg(PLL_VCLK_CNTL, vclkCntl & ~PLL_VCLK_RESET);