clk: composite: support determine_rate using rate_ops->round_rate + mux_ops->set_parent

A patch from »Clock support for rk3066,rk3188 and rk3288« in state Mainline for linux-kernel

From: Boris BREZILLON <b.brezillon@...> Date: Tue, 7 Jan 2014 18:03:52 +0100

Commit-Message

In case the rate_hw does not implement determine_rate, but only round_rate we fallback to best_parent selection if mux_hw is present and support reparenting. Signed-off-by: Boris BREZILLON <b.brezillon@...> This also fixes a rate calculation problem when using the standard div and mux ops, as in this case currently only the mux->determine_rate is used in the composite rate calculation. So when for example the composite clock has two parents at 600 and 800MHz, the requested rate is 75MHz, which the divider could provide, without this change the rate would be set 600MHz ignoring the divider completely. This may be way out of spec for the component. [fixed the output to actually return a rate instead of the diff] Signed-off-by: Heiko Stuebner <heiko@...>

Patch-Comment

drivers/clk/clk-composite.c | 51 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 50 insertions(+), 1 deletion(-)

Statistics

  • 50 lines added
  • 1 lines removed

Changes

------------------------- drivers/clk/clk-composite.c --------------------------
index 57a078e..0a4cd21 100644
@@ -64,11 +64,59 @@ static long clk_composite_determine_rate(struct clk_hw *hw, unsigned long rate,
const struct clk_ops *mux_ops = composite->mux_ops;
struct clk_hw *rate_hw = composite->rate_hw;
struct clk_hw *mux_hw = composite->mux_hw;
+ struct clk *parent;
+ unsigned long parent_rate;
+ long tmp_rate, best_rate;
+ unsigned long rate_diff;
+ unsigned long best_rate_diff = ULONG_MAX;
+ int i;
if (rate_hw && rate_ops && rate_ops->determine_rate) {
rate_hw->clk = hw->clk;
return rate_ops->determine_rate(rate_hw, rate, best_parent_rate,
best_parent_p);
+ } else if (rate_hw && rate_ops && rate_ops->round_rate &&
+ mux_hw && mux_ops && mux_ops->set_parent) {
+ *best_parent_p = NULL;
+
+ if (__clk_get_flags(hw->clk) & CLK_SET_RATE_NO_REPARENT) {
+ *best_parent_p = clk_get_parent(mux_hw->clk);
+ *best_parent_rate = __clk_get_rate(*best_parent_p);
+
+ return rate_ops->round_rate(rate_hw, rate,
+ best_parent_rate);
+ }
+
+ for (i = 0; i < __clk_get_num_parents(mux_hw->clk); i++) {
+ parent = clk_get_parent_by_index(mux_hw->clk, i);
+ if (!parent)
+ continue;
+
+ parent_rate = __clk_get_rate(parent);
+
+ tmp_rate = rate_ops->round_rate(rate_hw, rate,
+ &parent_rate);
+ if (tmp_rate < 0)
+ continue;
+
+ if (tmp_rate < rate)
+ rate_diff = rate - tmp_rate;
+ else
+ rate_diff = tmp_rate - rate;
+
+ if (!rate_diff || !*best_parent_p
+ || best_rate_diff > rate_diff) {
+ *best_parent_p = parent;
+ *best_parent_rate = parent_rate;
+ best_rate_diff = rate_diff;
+ best_rate = tmp_rate;
+ }
+
+ if (!rate_diff)
+ return rate;
+ }
+
+ return best_rate;
} else if (mux_hw && mux_ops && mux_ops->determine_rate) {
mux_hw->clk = hw->clk;
return mux_ops->determine_rate(mux_hw, rate, best_parent_rate,
@@ -196,7 +244,8 @@ struct clk *clk_register_composite(struct device *dev, const char *name,
composite->rate_hw = rate_hw;
composite->rate_ops = rate_ops;
clk_composite_ops->recalc_rate = clk_composite_recalc_rate;
- if (rate_ops->determine_rate)
+ if (rate_ops->determine_rate ||
+ (rate_ops->round_rate && clk_composite_ops->set_parent))
clk_composite_ops->determine_rate = clk_composite_determine_rate;
}
 
 

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