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>

diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c
index 9f5d636..67bbb06 100644 (file)
--- 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__);