23 	unsigned int p1;  in aptina_pll_calculate()  local
40 	/* Compute the multiplier M and combined N*P1 divisor. */  in aptina_pll_calculate()
45 	/* We now have the smallest M and N*P1 values that will result in the  in aptina_pll_calculate()
53 	 * - minimum/maximum combined N*P1 divisor  in aptina_pll_calculate()
66 		dev_err(dev, "pll: no valid combined N*P1 divisor.\n");  in aptina_pll_calculate()
71 	 * We're looking for the highest acceptable P1 value for which a  in aptina_pll_calculate()
74 	 * 1. p1 is in the [p1_min, p1_max] range given by the limits and is  in aptina_pll_calculate()
77 	 * 3. div * mf is a multiple of p1, in order to compute  in aptina_pll_calculate()
78 	 *	n = div * mf / p1  in aptina_pll_calculate()
85 	 * The first naive approach is to iterate over all p1 values acceptable  in aptina_pll_calculate()
86 	 * according to (1) and all mf values acceptable according to (2), and  in aptina_pll_calculate()
94 	 *	mf_inc = p1 / gcd(div, p1)			(6)  in aptina_pll_calculate()
100 	 * acceptable p1 and mf values by modifying the minimum and maximum  in aptina_pll_calculate()
103 	 *	ext_clock / (div * mf / p1) * m * mf >= out_clock_min  in aptina_pll_calculate()
104 	 *	ext_clock / (div * mf / p1) * m * mf <= out_clock_max  in aptina_pll_calculate()
108 	 *	p1 >= out_clock_min * div / (ext_clock * m)	(7)  in aptina_pll_calculate()
109 	 *	p1 <= out_clock_max * div / (ext_clock * m)  in aptina_pll_calculate()
113 	 *	mf >= ext_clock * p1 / (int_clock_max * div)	(8)  in aptina_pll_calculate()
114 	 *	mf <= ext_clock * p1 / (int_clock_min * div)  in aptina_pll_calculate()
116 	 * We can thus iterate over the restricted p1 range defined by the  in aptina_pll_calculate()
117 	 * combination of (1) and (7), and then compute the restricted mf range  in aptina_pll_calculate()
120 	 * select the mf lwoer bound and the corresponding p1 value.  in aptina_pll_calculate()
123 		dev_err(dev, "pll: P1 minimum value must be >0.\n");  in aptina_pll_calculate()
132 	for (p1 = p1_max & ~1; p1 >= p1_min; p1 -= 2) {  in aptina_pll_calculate()
133 		unsigned int mf_inc = p1 / gcd(div, p1);  in aptina_pll_calculate()
137 		mf_low = roundup(max(mf_min, DIV_ROUND_UP(pll->ext_clock * p1,  in aptina_pll_calculate()
139 		mf_high = min(mf_max, pll->ext_clock * p1 /  in aptina_pll_calculate()
145 		pll->n = div * mf_low / p1;  in aptina_pll_calculate()
147 		pll->p1 = p1;  in aptina_pll_calculate()
148 		dev_dbg(dev, "PLL: N %u M %u P1 %u\n", pll->n, pll->m, pll->p1);  in aptina_pll_calculate()
152 	dev_err(dev, "pll: no valid N and P1 divisors found.\n");  in aptina_pll_calculate()