On 02/14/2014 01:00 AM, Tony Lindgren wrote:

* Tomi Valkeinen [off-list ref] [140116 23:47]:

quoted

omap2_dpll_round_rate() doesn't actually round the given rate, even if
the name and the description so hints. Instead it only tries to find an
exact rate match, or if that fails, return ~0 as an error.

What this basically means is that the user of the clock needs to know
what rates the dpll can support, which obviously isn't right.

This patch adds a simple method of rounding: during the iteration, the
code keeps track of the closest rate match. If no exact match is found,
the closest is returned.

Signed-off-by: Tomi Valkeinen <redacted>

Paul & Tero, please ack if you want me to queue this.

The patches look good to me and based on quick testing they don't seem 
to cause any visible problems (namely this one), so acked.

-Tero

Tony

quoted

---
  arch/arm/mach-omap2/clkt_dpll.c | 17 ++++++++++++-----
  1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/arm/mach-omap2/clkt_dpll.c b/arch/arm/mach-omap2/clkt_dpll.c
index 1f1708ef77bb..1b4e68dfb713 100644
--- a/arch/arm/mach-omap2/clkt_dpll.c
+++ b/arch/arm/mach-omap2/clkt_dpll.c

@@ -298,6 +298,7 @@ long omap2_dpll_round_rate(struct clk_hw *hw, unsigned long target_rate,
  	struct dpll_data *dd;
  	unsigned long ref_rate;
  	const char *clk_name;
+	unsigned long diff, closest_diff = ~0;

  	if (!clk || !clk->dpll_data)
  		return ~0;

@@ -345,20 +346,26 @@ long omap2_dpll_round_rate(struct clk_hw *hw, unsigned long target_rate,
  		pr_debug("clock: %s: m = %d: n = %d: new_rate = %lu\n",
  			 clk_name, m, n, new_rate);

-		if (target_rate == new_rate) {
+		diff = max(target_rate, new_rate) - min(target_rate, new_rate);
+
+		if (diff < closest_diff) {
+			closest_diff = diff;
+
  			dd->last_rounded_m = m;
  			dd->last_rounded_n = n;
-			dd->last_rounded_rate = target_rate;
-			break;
+			dd->last_rounded_rate = new_rate;
+
+			if (diff == 0)
+				break;
  		}
  	}

-	if (target_rate != new_rate) {
+	if (closest_diff == ~0) {
  		pr_debug("clock: %s: cannot round to rate %lu\n",
  			 clk_name, target_rate);
  		return ~0;
  	}

-	return target_rate;
+	return dd->last_rounded_rate;
  }

--

1.8.3.2