Modify OMAP PLL rate rounding function to round to the exact rate requested

or the next one below it.  This is intended to resolve some DSS problems.
 
 Basic build, boot, and PM test results are available here:
 
 http://www.pwsan.com/omap/testlogs/clock-b-v3.17/20140725061121/
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Merge tag 'for-v3.17/omap-clock-b' of git://git.kernel.org/pub/scm/linux/kernel/git/pjw/omap-pending into omap-for-v3.17/soc

Modify OMAP PLL rate rounding function to round to the exact rate requested
or the next one below it.  This is intended to resolve some DSS problems.

Basic build, boot, and PM test results are available here:

http://www.pwsan.com/omap/testlogs/clock-b-v3.17/20140725061121/

arch/arm/mach-omap2/clkt_dpll.c

@@ -285,10 +285,13 @@ long omap2_dpll_round_rate(struct clk_hw *hw, unsigned long target_rate,
 {
 	struct clk_hw_omap *clk = to_clk_hw_omap(hw);
 	int m, n, r, scaled_max_m;
+	int min_delta_m = INT_MAX, min_delta_n = INT_MAX;
 	unsigned long scaled_rt_rp;
 	unsigned long new_rate = 0;
 	struct dpll_data *dd;
 	unsigned long ref_rate;
+	long delta;
+	long prev_min_delta = LONG_MAX;
 	const char *clk_name;
 
 	if (!clk || !clk->dpll_data)
@@ -334,23 +337,34 @@ long omap2_dpll_round_rate(struct clk_hw *hw, unsigned long target_rate,
 		if (r == DPLL_MULT_UNDERFLOW)
 			continue;
 
+		/* skip rates above our target rate */
+		delta = target_rate - new_rate;
+		if (delta < 0)
+			continue;
+
+		if (delta < prev_min_delta) {
+			prev_min_delta = delta;
+			min_delta_m = m;
+			min_delta_n = n;
+		}
+
 		pr_debug("clock: %s: m = %d: n = %d: new_rate = %lu\n",
 			 clk_name, m, n, new_rate);
 
-		if (target_rate == new_rate) {
-			dd->last_rounded_m = m;
-			dd->last_rounded_n = n;
-			dd->last_rounded_rate = target_rate;
+		if (delta == 0)
 			break;
-		}
 	}
 
-	if (target_rate != new_rate) {
+	if (prev_min_delta == LONG_MAX) {
 		pr_debug("clock: %s: cannot round to rate %lu\n",
 			 clk_name, target_rate);
 		return ~0;
 	}
 
-	return target_rate;
+	dd->last_rounded_m = min_delta_m;
+	dd->last_rounded_n = min_delta_n;
+	dd->last_rounded_rate = target_rate - prev_min_delta;
+
+	return dd->last_rounded_rate;
 }
 

arch/arm/mach-omap2/dpll3xxx.c

@@ -475,6 +475,7 @@ int omap3_noncore_dpll_set_rate(struct clk_hw *hw, unsigned long rate,
 {
 	struct clk_hw_omap *clk = to_clk_hw_omap(hw);
 	struct clk *new_parent = NULL;
+	unsigned long rrate;
 	u16 freqsel = 0;
 	struct dpll_data *dd;
 	int ret;
@@ -502,8 +503,16 @@ int omap3_noncore_dpll_set_rate(struct clk_hw *hw, unsigned long rate,
 		__clk_prepare(dd->clk_ref);
 		clk_enable(dd->clk_ref);
 
-		if (dd->last_rounded_rate != rate)
-			rate = __clk_round_rate(hw->clk, rate);
+		/* XXX this check is probably pointless in the CCF context */
+		if (dd->last_rounded_rate != rate) {
+			rrate = __clk_round_rate(hw->clk, rate);
+			if (rrate != rate) {
+				pr_warn("%s: %s: final rate %lu does not match desired rate %lu\n",
+					__func__, __clk_get_name(hw->clk),
+					rrate, rate);
+				rate = rrate;
+			}
+		}
 
 		if (dd->last_rounded_rate == 0)
 			return -EINVAL;