1 files changed, 65 insertions, 2 deletions

diff --git a/arch/arm/mach-omap2/clock.c b/arch/arm/mach-omap2/clock.c
index 76e20bcc4e8a..752e34787f21 100644
--- a/arch/arm/mach-omap2/clock.c
+++ b/arch/arm/mach-omap2/clock.c
@@ -58,12 +58,68 @@
 #define DPLL_ROUNDING_VAL               ((DPLL_SCALE_BASE / 2) * \
                                          (DPLL_SCALE_FACTOR / DPLL_SCALE_BASE))
 
+/* DPLL valid Fint frequency band limits - from 34xx TRM Section 4.7.6.2 */
+#define DPLL_FINT_BAND1_MIN             750000
+#define DPLL_FINT_BAND1_MAX             2100000
+#define DPLL_FINT_BAND2_MIN             7500000
+#define DPLL_FINT_BAND2_MAX             21000000
+
+/* _dpll_test_fint() return codes */
+#define DPLL_FINT_UNDERFLOW             -1
+#define DPLL_FINT_INVALID               -2
+
 u8 cpu_mask;
 
 /*-------------------------------------------------------------------------
  * OMAP2/3 specific clock functions
  *-------------------------------------------------------------------------*/
 
+/*
+ * _dpll_test_fint - test whether an Fint value is valid for the DPLL
+ * @clk: DPLL struct clk to test
+ * @n: divider value (N) to test
+ *
+ * Tests whether a particular divider @n will result in a valid DPLL
+ * internal clock frequency Fint. See the 34xx TRM 4.7.6.2 "DPLL Jitter
+ * Correction".  Returns 0 if OK, -1 if the enclosing loop can terminate
+ * (assuming that it is counting N upwards), or -2 if the enclosing loop
+ * should skip to the next iteration (again assuming N is increasing).
+ */
+static int _dpll_test_fint(struct clk *clk, u8 n)
+{
+        struct dpll_data *dd;
+        long fint;
+        int ret = 0;
+
+        dd = clk->dpll_data;
+
+        /* DPLL divider must result in a valid jitter correction val */
+        fint = clk->parent->rate / (n + 1);
+        if (fint < DPLL_FINT_BAND1_MIN) {
+
+                pr_debug("rejecting n=%d due to Fint failure, "
+                         "lowering max_divider\n", n);
+                dd->max_divider = n;
+                ret = DPLL_FINT_UNDERFLOW;
+
+        } else if (fint > DPLL_FINT_BAND1_MAX &&
+                   fint < DPLL_FINT_BAND2_MIN) {
+
+                pr_debug("rejecting n=%d due to Fint failure\n", n);
+                ret = DPLL_FINT_INVALID;
+
+        } else if (fint > DPLL_FINT_BAND2_MAX) {
+
+                pr_debug("rejecting n=%d due to Fint failure, "
+                         "boosting min_divider\n", n);
+                dd->min_divider = n;
+                ret = DPLL_FINT_INVALID;
+
+        }
+
+        return ret;
+}
+
 /**
  * omap2_init_clk_clkdm - look up a clockdomain name, store pointer in clk
  * @clk: OMAP clock struct ptr to use
@@ -892,7 +948,14 @@ long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate)
 
         dd->last_rounded_rate = 0;
 
-        for (n = DPLL_MIN_DIVIDER; n <= dd->max_divider; n++) {
+        for (n = dd->min_divider; n <= dd->max_divider; n++) {
+
+                /* Is the (input clk, divider) pair valid for the DPLL? */
+                r = _dpll_test_fint(clk, n);
+                if (r == DPLL_FINT_UNDERFLOW)
+                        break;
+                else if (r == DPLL_FINT_INVALID)
+                        continue;
 
                 /* Compute the scaled DPLL multiplier, based on the divider */
                 m = scaled_rt_rp * n;
@@ -926,7 +989,7 @@ long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate)
                         pr_debug("clock: found new least error %d\n", min_e);
 
                         /* We found good settings -- bail out now */
-                        if (min_e <= clk->dpll_data->rate_tolerance)
+                        if (min_e <= dd->rate_tolerance)
                                 break;
                 }
         }