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 ---
drivers/clk/clk_kendryte.c | 24 ++++++++++++++++++++++++ test/dm/k210_pll.c | 4 ++++ 2 files changed, 28 insertions(+)
diff --git a/drivers/clk/clk_kendryte.c b/drivers/clk/clk_kendryte.c index d2cee2cf97..e90550ef33 100644 --- a/drivers/clk/clk_kendryte.c +++ b/drivers/clk/clk_kendryte.c @@ -816,6 +816,30 @@ again: 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 5574ac96fa..f55379f336 100644 --- a/test/dm/k210_pll.c +++ b/test/dm/k210_pll.c @@ -84,6 +84,10 @@ static int dm_test_k210_pll(struct unit_test_state *uts) 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; }