cpufreq: OMAP: specify range for voltage scaling

Specify voltage in ranges for regulator. Range
used is tolerance specified for OPP.

This helps to achieve DVFS with a wider range of
regulators.

Cc: Kevin Hilman <khilman@ti.com>
Cc: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Afzal Mohammed <afzal@ti.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c
index 9f5d6368766e..67bbb06d0460 100644
--- a/drivers/cpufreq/omap-cpufreq.c
+++ b/drivers/cpufreq/omap-cpufreq.c
@@ -38,6 +38,9 @@
 
 #include <mach/hardware.h>
 
+/* OPP tolerance in percentage */
+#define OPP_TOLERANCE   4
+
 #ifdef CONFIG_SMP
 struct lpj_info {
         unsigned long   ref;
@@ -81,7 +84,7 @@ static int omap_target(struct cpufreq_policy *policy,
         int r, ret = 0;
         struct cpufreq_freqs freqs;
         struct opp *opp;
-        unsigned long freq, volt = 0, volt_old = 0;
+        unsigned long freq, volt = 0, volt_old = 0, tol = 0;
 
         if (!freq_table) {
                 dev_err(mpu_dev, "%s: cpu%d: no freq table!\n", __func__,
@@ -125,6 +128,7 @@ static int omap_target(struct cpufreq_policy *policy,
                         return -EINVAL;
                 }
                 volt = opp_get_voltage(opp);
+                tol = volt * OPP_TOLERANCE / 100;
                 volt_old = regulator_get_voltage(mpu_reg);
         }
 
@@ -134,7 +138,7 @@ static int omap_target(struct cpufreq_policy *policy,
 
         /* scaling up?  scale voltage before frequency */
         if (mpu_reg && (freqs.new > freqs.old)) {
-                r = regulator_set_voltage(mpu_reg, volt, volt);
+                r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
                 if (r < 0) {
                         dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
                                  __func__);
@@ -147,7 +151,7 @@ static int omap_target(struct cpufreq_policy *policy,
 
         /* scaling down?  scale voltage after frequency */
         if (mpu_reg && (freqs.new < freqs.old)) {
-                r = regulator_set_voltage(mpu_reg, volt, volt);
+                r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
                 if (r < 0) {
                         dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
                                  __func__);