Changeset fde2dab9 in mainline for uspace/drv/infrastructure/rootamdm37x/rootamdm37x.c

Timestamp:

2012-11-20T14:57:30Z (12 years ago)

Author:

Jan Vesely <jano.vesely@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

8138d4f

Parents:

bf2a269

Message:

rootamdm37x: Fix off by one freq calculations.

File:

• uspace/drv/infrastructure/rootamdm37x/rootamdm37x.c (modified) (3 diffs)

uspace/drv/infrastructure/rootamdm37x/rootamdm37x.c

@@ -179 +179 @@
                                 & MPU_CM_CLKSEL2_PLL_MPU_DPLL_CLKOUT_DIV_MASK);
                         if (multiplier && divisor && divisor2) {
+                                /** See AMDM37x TRM p. 300 for the formula */
                                 const unsigned freq =
-                                    ((base_freq / divisor) * multiplier) / divisor2;
+                                    ((base_freq * multiplier) / (divisor + 1))
+                                    / divisor2;
                                 ddf_msg(LVL_NOTE, "MPU running at %d.%d MHz",
                                     freq / 1000, freq % 1000);
@@ -238 +240 @@
                     CLOCK_CONTROL_CM_CLKSEL1_PLL_CORE_DPLL_CLKOUT_DIV_GET(reg);
                 if (multiplier && divisor && divisor2) {
+                        /** See AMDM37x TRM p. 300 for the formula */
                         const unsigned freq =
-                            ((base_freq / divisor) * multiplier) / divisor2;
+                            ((base_freq * multiplier) / (divisor + 1)) / divisor2;
                         ddf_msg(LVL_NOTE, "CORE CLK running at %d.%d MHz",
                             freq / 1000, freq % 1000);
@@ -288 +291 @@
                 & CLOCK_CONTROL_CM_CLKEN2_PLL_EN_PERIPH2_DPLL_MASK)
             != CLOCK_CONTROL_CM_CLKEN2_PLL_EN_PERIPH2_DPLL_LOCK) {
-                /* Compute divisors and multiplier */
+                /* Compute divisors and multiplier
+                 * See AMDM37x TRM p. 300 for the formula */
                 assert((base_freq % 100) == 0);
                 const unsigned mult = 1200;
-                const unsigned div = base_freq / 100;
+                const unsigned div = (base_freq / 100) - 1;
                 const unsigned div2 = 1;