Quoting Chen-Yu Tsai (2016-07-13 20:34:34)

On Sat, Jul 9, 2016 at 2:36 AM, Michael Turquette
[off-list ref] wrote:

quoted

Quoting Chen-Yu Tsai (2016-06-30 08:58:48)

quoted

+static long ac100_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
+                                   unsigned long prate)
+{
+       unsigned long best_rate = 0, tmp_rate, tmp_prate;
+       int i;
+
+       if (prate == AC100_RTC_32K_RATE)
+               return divider_round_rate(hw, rate, &prate, NULL,
+                                         AC100_CLKOUT_DIV_WIDTH,
+                                         CLK_DIVIDER_POWER_OF_TWO);
+
+       for (i = 0; ac100_clkout_prediv[i].div; i++) {
+               tmp_prate = DIV_ROUND_UP(prate, ac100_clkout_prediv[i].val);
+               tmp_rate = divider_round_rate(hw, rate, &tmp_prate, NULL,
+                                             AC100_CLKOUT_DIV_WIDTH,
+                                             CLK_DIVIDER_POWER_OF_TWO);
+
+               if (tmp_rate > rate)
+                       continue;
+               if (rate - tmp_rate < best_rate - tmp_rate)
+                       best_rate = tmp_rate;
+       }
+
+       return best_rate;
+}
+
+static int ac100_clkout_determine_rate(struct clk_hw *hw,
+                                      struct clk_rate_request *req)
+{
+       struct clk_hw *best_parent;
+       unsigned long best = 0;
+       int i, num_parents = clk_hw_get_num_parents(hw);
+
+       for (i = 0; i < num_parents; i++) {
+               struct clk_hw *parent = clk_hw_get_parent_by_index(hw, i);
+               unsigned long tmp, prate = clk_hw_get_rate(parent);
+
+               tmp = ac100_clkout_round_rate(hw, req->rate, prate);
+
+               if (tmp > req->rate)
+                       continue;
+               if (req->rate - tmp < req->rate - best) {
+                       best = tmp;
+                       best_parent = parent;
+               }
+       }
+
+       if (!best)
+               return -EINVAL;
+
+       req->best_parent_hw = best_parent;
+       req->best_parent_rate = best;
+       req->rate = best;
+
+       return 0;
+}

You only need one of the two functions above. Keep the .determine_rate
callback and drop .round_rate.

Only .round_rate is set in the clk_ops. ac100_clkout_round_rate just
serves to split out some of the calculations done per parent.

If you only use .round_rate, shouldn't you drop .determine_rate then?

Regards,
Mike

quoted

Otherwise the rest of the clk support looks great to me. Feel free to
add:

Reviewed-by: Michael Turquette <mturquette@baylibre.com>

Thanks!

ChenYu