ARM: OMAP2+: clock: allow omap2_dpll_round_rate() to round to next-lowest rate

Change the behavior of omap2_dpll_round_rate() to round to either the
exact rate requested, or the next lowest rate that the clock is able to
provide.

This is not an ideal fix, but is intended to provide a relatively safe
way for drivers to set PLL rates, until a better solution can be
implemented.

For the time being, omap3_noncore_dpll_set_rate() is still allowed to
set its rate to something other than what the caller requested; but will
warn when this occurs.

Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Paul Walmsley <paul@pwsan.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/arch/arm/mach-omap2/dpll3xxx.c b/arch/arm/mach-omap2/dpll3xxx.c
index 6d7ba37e2257..b6860bfb05b3 100644
--- a/arch/arm/mach-omap2/dpll3xxx.c
+++ b/arch/arm/mach-omap2/dpll3xxx.c
@@ -478,6 +478,7 @@ 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;
@@ -505,8 +506,16 @@ 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;