[PATCH] ARM: OMAP2+: voltage: ensure voltage used is exact voltage from OPP table

[PATCH] ARM: OMAP2+: voltage: ensure voltage used is exact voltage from OPP table

[Kevin Hilman]

When using the SMPS regulators to scale voltages, the regulator
framework may pass a minimum voltage that is not an exact OPP voltage.
For the VC/VP controlled voltage domains, we must ensure that the
voltage requested is the exact voltage from the OPP table.  This is
especially critical when using SR.

To fix, voltdm_scale() uses the target voltage passed to walk through
the OPP voltages until it finds a voltage that is >= one of the OPP
voltages.

Cc: Tero Kristo <t-kristo@ti.com>
Cc: Nishanth Menon <nm@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
---
Unless there are any objections, this will be queued along with the
rest of the SMPS regulator series from Tero.  Currently availble in
my for_3.4/pm/smps-regulator branch at
git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-omap-pm.git

 arch/arm/mach-omap2/voltage.c |   21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-omap2/voltage.c b/arch/arm/mach-omap2/voltage.c
index 8a36342..4dc60e8 100644
--- a/arch/arm/mach-omap2/voltage.c
+++ b/arch/arm/mach-omap2/voltage.c
@@ -73,7 +73,8 @@ unsigned long voltdm_get_voltage(struct voltagedomain *voltdm)
 int voltdm_scale(struct voltagedomain *voltdm,
 		 unsigned long target_volt)
 {
-	int ret;
+	int ret, i;
+	unsigned long volt = 0;
 
 	if (!voltdm || IS_ERR(voltdm)) {
 		pr_warning("%s: VDD specified does not exist!\n", __func__);
@@ -86,9 +87,23 @@ int voltdm_scale(struct voltagedomain *voltdm,
 		return -ENODATA;
 	}
 
-	ret = voltdm->scale(voltdm, target_volt);
+	/* Adjust voltage to the exact voltage from the OPP table */
+	for (i = 0; voltdm->volt_data[i].volt_nominal != 0; i++) {
+		if (voltdm->volt_data[i].volt_nominal >= target_volt) {
+			volt = voltdm->volt_data[i].volt_nominal;
+			break;
+		}
+	}
+
+	if (!volt) {
+		pr_warning("%s: not scaling. OPP voltage for %lu, not found.\n",
+			   __func__, target_volt);
+		return -EINVAL;
+	}
+
+	ret = voltdm->scale(voltdm, volt);
 	if (!ret)
-		voltdm->nominal_volt = target_volt;
+		voltdm->nominal_volt = volt;
 
 	return ret;
 }
-- 
1.7.9.2

[PATCH] ARM: OMAP2+: voltage: ensure voltage used is exact voltage from OPP table

[Tero Kristo]

On Fri, 2012-03-02 at 14:42 -0800, Kevin Hilman wrote:
> When using the SMPS regulators to scale voltages, the regulator
> framework may pass a minimum voltage that is not an exact OPP voltage.
> For the VC/VP controlled voltage domains, we must ensure that the
> voltage requested is the exact voltage from the OPP table.  This is
> especially critical when using SR.
> 
> To fix, voltdm_scale() uses the target voltage passed to walk through
> the OPP voltages until it finds a voltage that is >= one of the OPP
> voltages.

I have just one question to this, how about smartreflex class1p5? Do we
have any plans for that one? The old implementation at least was using
voltdm_scale, so if we modify this function, smartreflex class1p5
doesn't work anymore.

Otherwise this patch looks good to me.

-Tero

> 
> Cc: Tero Kristo <t-kristo@ti.com>
> Cc: Nishanth Menon <nm@ti.com>
> Signed-off-by: Kevin Hilman <khilman@ti.com>
> ---
> Unless there are any objections, this will be queued along with the
> rest of the SMPS regulator series from Tero.  Currently availble in
> my for_3.4/pm/smps-regulator branch at
> git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-omap-pm.git
> 
>  arch/arm/mach-omap2/voltage.c |   21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/voltage.c b/arch/arm/mach-omap2/voltage.c
> index 8a36342..4dc60e8 100644
> --- a/arch/arm/mach-omap2/voltage.c
> +++ b/arch/arm/mach-omap2/voltage.c
> @@ -73,7 +73,8 @@ unsigned long voltdm_get_voltage(struct voltagedomain *voltdm)
>  int voltdm_scale(struct voltagedomain *voltdm,
>  		 unsigned long target_volt)
>  {
> -	int ret;
> +	int ret, i;
> +	unsigned long volt = 0;
>  
>  	if (!voltdm || IS_ERR(voltdm)) {
>  		pr_warning("%s: VDD specified does not exist!\n", __func__);
> @@ -86,9 +87,23 @@ int voltdm_scale(struct voltagedomain *voltdm,
>  		return -ENODATA;
>  	}
>  
> -	ret = voltdm->scale(voltdm, target_volt);
> +	/* Adjust voltage to the exact voltage from the OPP table */
> +	for (i = 0; voltdm->volt_data[i].volt_nominal != 0; i++) {
> +		if (voltdm->volt_data[i].volt_nominal >= target_volt) {
> +			volt = voltdm->volt_data[i].volt_nominal;
> +			break;
> +		}
> +	}
> +
> +	if (!volt) {
> +		pr_warning("%s: not scaling. OPP voltage for %lu, not found.\n",
> +			   __func__, target_volt);
> +		return -EINVAL;
> +	}
> +
> +	ret = voltdm->scale(voltdm, volt);
>  	if (!ret)
> -		voltdm->nominal_volt = target_volt;
> +		voltdm->nominal_volt = volt;
>  
>  	return ret;
>  }

[PATCH] ARM: OMAP2+: voltage: ensure voltage used is exact voltage from OPP table

[Kevin Hilman]

Tero Kristo <t-kristo@ti.com> writes:

> On Fri, 2012-03-02 at 14:42 -0800, Kevin Hilman wrote:
>> When using the SMPS regulators to scale voltages, the regulator
>> framework may pass a minimum voltage that is not an exact OPP voltage.
>> For the VC/VP controlled voltage domains, we must ensure that the
>> voltage requested is the exact voltage from the OPP table.  This is
>> especially critical when using SR.
>> 
>> To fix, voltdm_scale() uses the target voltage passed to walk through
>> the OPP voltages until it finds a voltage that is >= one of the OPP
>> voltages.
>
> I have just one question to this, how about smartreflex class1p5? Do we
> have any plans for that one? The old implementation at least was using
> voltdm_scale, so if we modify this function, smartreflex class1p5
> doesn't work anymore.

Since it's not in mainline, that is not my concern at the moment.  We
can worry about SR1.5 when I someone is motivated to push it upstream.

> Otherwise this patch looks good to me.

Thanks for looking.

Kevin

[PATCH] ARM: OMAP2+: voltage: ensure voltage used is exact voltage from OPP table

[Nishanth Menon]

On 10:12-20120305, Kevin Hilman wrote:
> Tero Kristo <t-kristo@ti.com> writes:
> 
> > On Fri, 2012-03-02 at 14:42 -0800, Kevin Hilman wrote:
> >> When using the SMPS regulators to scale voltages, the regulator
> >> framework may pass a minimum voltage that is not an exact OPP voltage.
> >> For the VC/VP controlled voltage domains, we must ensure that the
> >> voltage requested is the exact voltage from the OPP table.  This is
> >> especially critical when using SR.
> >> 
> >> To fix, voltdm_scale() uses the target voltage passed to walk through
> >> the OPP voltages until it finds a voltage that is >= one of the OPP
> >> voltages.
> >
> > I have just one question to this, how about smartreflex class1p5? Do we
> > have any plans for that one? The old implementation at least was using
> > voltdm_scale, so if we modify this function, smartreflex class1p5
> > doesn't work anymore.
> 
> Since it's not in mainline, that is not my concern at the moment.  We
> can worry about SR1.5 when I someone is motivated to push it upstream.
> 
> > Otherwise this patch looks good to me.

Other than the minor misgiving of having to re-verify the voltage on
every scale, I am OK with it as well.

That said, I don't see why this should break class 1.5/3.5 support.

-- 
Regards,
Nishanth Menon