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authorFrank Oltmanns <frank@oltmanns.dev>2023-08-07 14:43:35 +0200
committerChen-Yu Tsai <wens@csie.org>2023-08-09 17:33:58 +0200
commit3492e4f6db5f6814869a4639d70ea025385f4cb6 (patch)
tree79c3e0752c75f164de7b386b3ed25232b59441d4 /drivers/clk
parentclk: sunxi-ng: nkm: Use correct parameter name for parent HW (diff)
downloadlinux-3492e4f6db5f6814869a4639d70ea025385f4cb6.tar.xz
linux-3492e4f6db5f6814869a4639d70ea025385f4cb6.zip
clk: sunxi-ng: nkm: consider alternative parent rates when determining rate
In case the CLK_SET_RATE_PARENT flag is set, consider using a different parent rate when determining a new rate. To find the best match for the requested rate, perform the following steps for each NKM combination: - calculate the optimal parent rate, - find the best parent rate that the parent clock actually supports - use that parent rate to calculate the effective rate. In case the clk does not support setting the parent rate, use the same algorithm as before. Acked-by: Maxime Ripard <mripard@kernel.org> Signed-off-by: Frank Oltmanns <frank@oltmanns.dev> Reviewed-by: Chen-Yu Tsai <wens@csie.org> Link: https://lore.kernel.org/r/20230807-pll-mipi_set_rate_parent-v6-2-f173239a4b59@oltmanns.dev Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Diffstat (limited to 'drivers/clk')
-rw-r--r--drivers/clk/sunxi-ng/ccu_nkm.c44
1 files changed, 43 insertions, 1 deletions
diff --git a/drivers/clk/sunxi-ng/ccu_nkm.c b/drivers/clk/sunxi-ng/ccu_nkm.c
index f267142e58b3..2f60f3c33e30 100644
--- a/drivers/clk/sunxi-ng/ccu_nkm.c
+++ b/drivers/clk/sunxi-ng/ccu_nkm.c
@@ -16,6 +16,45 @@ struct _ccu_nkm {
unsigned long m, min_m, max_m;
};
+static unsigned long ccu_nkm_find_best_with_parent_adj(struct clk_hw *parent_hw,
+ unsigned long *parent, unsigned long rate,
+ struct _ccu_nkm *nkm)
+{
+ unsigned long best_rate = 0, best_parent_rate = *parent, tmp_parent = *parent;
+ unsigned long best_n = 0, best_k = 0, best_m = 0;
+ unsigned long _n, _k, _m;
+
+ for (_k = nkm->min_k; _k <= nkm->max_k; _k++) {
+ for (_n = nkm->min_n; _n <= nkm->max_n; _n++) {
+ for (_m = nkm->min_m; _m <= nkm->max_m; _m++) {
+ unsigned long tmp_rate;
+
+ tmp_parent = clk_hw_round_rate(parent_hw, rate * _m / (_n * _k));
+
+ tmp_rate = tmp_parent * _n * _k / _m;
+ if (tmp_rate > rate)
+ continue;
+
+ if ((rate - tmp_rate) < (rate - best_rate)) {
+ best_rate = tmp_rate;
+ best_parent_rate = tmp_parent;
+ best_n = _n;
+ best_k = _k;
+ best_m = _m;
+ }
+ }
+ }
+ }
+
+ nkm->n = best_n;
+ nkm->k = best_k;
+ nkm->m = best_m;
+
+ *parent = best_parent_rate;
+
+ return best_rate;
+}
+
static unsigned long ccu_nkm_find_best(unsigned long parent, unsigned long rate,
struct _ccu_nkm *nkm)
{
@@ -124,7 +163,10 @@ static unsigned long ccu_nkm_round_rate(struct ccu_mux_internal *mux,
if (nkm->common.features & CCU_FEATURE_FIXED_POSTDIV)
rate *= nkm->fixed_post_div;
- rate = ccu_nkm_find_best(*parent_rate, rate, &_nkm);
+ if (!clk_hw_can_set_rate_parent(&nkm->common.hw))
+ rate = ccu_nkm_find_best(*parent_rate, rate, &_nkm);
+ else
+ rate = ccu_nkm_find_best_with_parent_adj(parent_hw, parent_rate, rate, &_nkm);
if (nkm->common.features & CCU_FEATURE_FIXED_POSTDIV)
rate /= nkm->fixed_post_div;