Re: [PATCH] cpufreq: OMAP: specify range for voltage scaling

[Kevin Hilman <khilman@ti.com>]

Afzal Mohammed <afzal@ti.com> writes:

> 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>

Thanks, will queue this with the CPUfreq changes for MPU DVFS.

Kevin

> ---
> Hi,
>
> Tolerance specified here is that of AM335X, least value
> of tolerance that I could find so far for OMAP family
>
> This applies on top of Kevin Hilman's patch (v2),
> "cpufreq: OMAP: scale voltage along with frequency"
> http://www.spinics.net/lists/linux-omap/msg65002.html
>
> Regards
> Afzal
>
>  drivers/cpufreq/omap-cpufreq.c |   10 +++++++---
>  1 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c
> index 10b8e23..3cea51b 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__);