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pbkit: Dynamically compute PTIMER parameters #775

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68 changes: 43 additions & 25 deletions lib/pbkit/pbkit.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2180,10 +2180,38 @@ void pb_set_color_format(unsigned int fmt, bool swizzled)
assert(swizzled == false);
}

/**
* Helper function to calculate numerator and denominator for PTIMER
*
* It takes nvclk as input and scales the 31.25MHz/nvclk fraction down into
* the 16 bit value range of PTIMER parameters. It's not a perfect approach,
* but more accurate than the hardcoded values of the XDK, while properly
* scaling with overclocking.
*
* PTIMER is just a wall clock used for timestamps anyway.
*/
static inline void pb_calc_ptimer_param (uint32_t nvclk, uint32_t *denominator, uint32_t *numerator)
{
uint32_t num = nvclk;
uint32_t den = 31250000;

const uint32_t max_val = 1 << 16;
const uint32_t scale_num = (num + max_val - 1) / max_val;
const uint32_t scale_den = (den + max_val - 1) / max_val;
const uint32_t scale = (scale_num > scale_den) ? scale_num : scale_den;

if (scale > 1) {
num = (num + scale - 1) / scale;
den = (den + scale - 1) / scale;
}

*numerator = num;
*denominator = den;
}

int pb_init(void)
{
DWORD old;
DWORD mdiv,ndiv,odiv,pdiv,result;

BYTE old_color_31;
BYTE old_color_82;
Expand Down Expand Up @@ -2350,33 +2378,23 @@ int pb_init(void)
VIDEOREG(NV_PMC_ENABLE)=NV_PMC_ENABLE_ALL_ENABLE;
VIDEOREG(NV_PMC_INTR_EN_0)=NV_PMC_INTR_EN_0_INTA_HARDWARE;

mdiv=(VIDEOREG(NV_PRAMDAC_NVPLL_COEFF)&NV_PRAMDAC_NVPLL_COEFF_MDIV);
ndiv=(VIDEOREG(NV_PRAMDAC_NVPLL_COEFF)&NV_PRAMDAC_NVPLL_COEFF_NDIV)>>8;
odiv=1;
pdiv=(VIDEOREG(NV_PRAMDAC_NVPLL_COEFF)&NV_PRAMDAC_NVPLL_COEFF_PDIV)>>16;

if (mdiv)
{
//Xtal in Xbox is at 16.666 Mhz but we want 31.25Mhz for GPU...
if (((DW_XTAL_16MHZ*ndiv)/(odiv<<pdiv))/mdiv!=233333324)
{
//This PLL configuration doesn't create a 233.33 Mhz freq from Xtal
//Have this issure reported so we can update source for that case
debugPrint("PLL=%lu\n",((DW_XTAL_16MHZ*ndiv)/(odiv<<pdiv))/mdiv);
return -5;
}
}
else
// Configure PTIMER to 31.25MHz
{
pb_kill();
return -5; //invalid GPU internal PLL (Phase Locked Loop=GPU freq generator)
}
uint32_t mdiv = (VIDEOREG(NV_PRAMDAC_NVPLL_COEFF) & NV_PRAMDAC_NVPLL_COEFF_MDIV);
uint32_t ndiv = (VIDEOREG(NV_PRAMDAC_NVPLL_COEFF) & NV_PRAMDAC_NVPLL_COEFF_NDIV) >> 8;
uint32_t pdiv = (VIDEOREG(NV_PRAMDAC_NVPLL_COEFF) & NV_PRAMDAC_NVPLL_COEFF_PDIV) >> 16;

//program GPU timer in order to obtain 31.25Mhz (we assume PLL creates 233.33Mhz)
VIDEOREG(NV_PTIMER_NUMERATOR)=56968; //233333324/56968*7629=31247365 (31.25Mhz)
VIDEOREG(NV_PTIMER_DENOMINATOR)=7629;
if (!mdiv) {
pb_kill();
return -5; //invalid GPU internal PLL (Phase Locked Loop=GPU freq generator)
}

VIDEOREG(NV_PTIMER_ALARM_0)=0xFFFFFFFF;
uint32_t num, den;
pb_calc_ptimer_param(((DW_XTAL_16MHZ * ndiv) / (1 << pdiv)) / mdiv, &den, &num);
VIDEOREG(NV_PTIMER_NUMERATOR) = num - 1;
VIDEOREG(NV_PTIMER_DENOMINATOR) = den - 1;
VIDEOREG(NV_PTIMER_ALARM_0) = 0xFFFFFFFF;
}


//The Gpu instance memory is a special place in PRAMIN area (VRAM attached to RAM?)
Expand Down
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