RE: [PATCH v15 05/10] clk: Add Sunplus SP7021 clock driver

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+
+                               df_quotient  = df / m;
+                               df_remainder = ((df % m) * 1000) / m;
+
+                               if (freq > df_quotient) {
+                                       df_quotient  = freq - df_quotient - 1;
+                                       df_remainder = 1000 - df_remainder;

Where does 1000 come from?

1000 is come from "borrow 1" in last operation.

It's scaling the value right? What is being scaled? Are we converting
units to Hz from kHz?

Here just using integer replacement floating point operation, for example:
df = 13, m = 3
13 / 3 = 4.33333333
df_quotient = 4
df_remainder = 0.3333333 * 1000 (accurate to 3 decimal places) = 333