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Diffstat (limited to 'src/soc/nvidia/tegra124/clock.c')
-rw-r--r--src/soc/nvidia/tegra124/clock.c23
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)