clk: k210: Try harder to get the best config
In some cases, the best config cannot be used because the VCO would be
out-of-spec. In these cases, we may need to try a worse combination of r/od
in order to find the best representable config. This also adds a few test
cases to catch this and other (possible) unlikely errors.
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/clk/clk_kendryte.c b/drivers/clk/clk_kendryte.c
index 69691c4..97efda5 100644
--- a/drivers/clk/clk_kendryte.c
+++ b/drivers/clk/clk_kendryte.c
@@ -816,6 +816,30 @@
i--;
}
+ /*
+ * Try looking back to see if there is a worse ratio
+ * that we could try anyway
+ */
+ while (i > 0) {
+ i--;
+ new_r = UNPACK_R(factors[i]);
+ new_od = UNPACK_OD(factors[i]);
+ /*
+ * Don't loop over factors for the same product
+ * to avoid getting stuck because of the above
+ * clause
+ */
+ if (r * od != new_r * new_od) {
+ if (new_r * new_od > last_r * last_od) {
+ r = new_r;
+ od = new_od;
+ swapped = false;
+ goto again;
+ }
+ break;
+ }
+ }
+
/* We ran out of things to try */
continue;
}
diff --git a/test/dm/k210_pll.c b/test/dm/k210_pll.c
index 5574ac9..f55379f 100644
--- a/test/dm/k210_pll.c
+++ b/test/dm/k210_pll.c
@@ -84,6 +84,10 @@
compare(400000000, 26000000);
compare(27000000, 26000000);
compare(26000000, 27000000);
+ compare(13300000 * 64, 13300000);
+ compare(21250000, 21250000 * 70);
+ compare(21250000, 1750000000);
+ compare(1750000000, 1750000000);
return 0;
}