diff options
Diffstat (limited to 'src/soc/nvidia/tegra124/clock.c')
| -rw-r--r-- | src/soc/nvidia/tegra124/clock.c | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/src/soc/nvidia/tegra124/clock.c b/src/soc/nvidia/tegra124/clock.c index eed5116c32..c5b06f4557 100644 --- a/src/soc/nvidia/tegra124/clock.c +++ b/src/soc/nvidia/tegra124/clock.c @@ -304,7 +304,8 @@ clock_display(u32 frequency) * = (cf * n) >> p, where 1MHz < cf < 6MHz * = ((ref / m) * n) >> p * - * Assume p = 0, find best (m, n). since m has only 5 bits, we can + * Iterate the possible values of p (3 bits, 2^7) to find out a minimum + * safe vco, then find best (m, n). since m has only 5 bits, we can * iterate all possible values. Note Tegra 124 supports 11 bits for n, * but our pll_fields has only 10 bits for n. * @@ -312,19 +313,25 @@ clock_display(u32 frequency) * work if the values are not in "safe" range by panel specification. */ struct pllpad_dividers plld = { 0 }; - u32 ref = clock_get_pll_input_khz() * 1000, m, n; - u32 cf, vco = frequency; - u32 diff, best_diff = vco; - const u32 max_m = 1 << 5, max_n = 1 << 10, mhz = 1000 * 1000, - min_vco = 500 * mhz, max_vco = 1000 * mhz, + u32 ref = clock_get_pll_input_khz() * 1000, m, n, p = 0; + u32 cf, vco; + u32 diff, best_diff; + const u32 max_m = 1 << 5, max_n = 1 << 10, max_p = 1 << 3, + mhz = 1000 * 1000, min_vco = 500 * mhz, max_vco = 1000 * mhz, min_cf = 1 * mhz, max_cf = 6 * mhz; + for (vco = frequency; vco < min_vco && p < max_p; p++) + vco <<= 1; + if (vco < min_vco || vco > max_vco) { - printk(BIOS_ERR, "%s: VCO (%d) out of range. Cannot support.\n", - __func__, vco); + printk(BIOS_ERR, "%s: Cannot find out a supported VCO" + " for Frequency (%u).\n", __func__, frequency); return -1; } + plld.p = p; + best_diff = vco; + for (m = 1; m < max_m && best_diff; m++) { cf = ref / m; if (cf < min_cf) |