diff mbox

[3/5] cpufreq: imx6q: Set max suspend_freq to avoid changes during suspend

Message ID 94d99b261124b813adecf11e86a0ffe05c37f276.1490987945.git.leonard.crestez@nxp.com (mailing list archive)
State New, archived
Headers show

Commit Message

Leonard Crestez March 31, 2017, 7:25 p.m. UTC
If the cpufreq driver tries to modify voltage/freq during suspend/resume
it might need to control an external PMIC via I2C or SPI but those
devices might be already suspended.

To avoid this scenario we just increase cpufreq to highest setpoint
before suspend. This issue can easily be triggered by ldo-bypass but in
theory any regulator set_voltage call can end up having to modify
external supply voltages.

Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/imx6q-cpufreq.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Lucas Stach April 4, 2017, 9:51 a.m. UTC | #1
Am Freitag, den 31.03.2017, 22:25 +0300 schrieb Leonard Crestez:
> If the cpufreq driver tries to modify voltage/freq during suspend/resume
> it might need to control an external PMIC via I2C or SPI but those
> devices might be already suspended.
> 
> To avoid this scenario we just increase cpufreq to highest setpoint
> before suspend. This issue can easily be triggered by ldo-bypass but in
> theory any regulator set_voltage call can end up having to modify
> external supply voltages.
> 
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  drivers/cpufreq/imx6q-cpufreq.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
> index be90ee3..e2c1fbf 100644
> --- a/drivers/cpufreq/imx6q-cpufreq.c
> +++ b/drivers/cpufreq/imx6q-cpufreq.c
> @@ -162,6 +162,7 @@ static int imx6q_set_target(struct cpufreq_policy *policy, unsigned int index)
>  static int imx6q_cpufreq_init(struct cpufreq_policy *policy)
>  {
>  	policy->clk = arm_clk;
> +	policy->suspend_freq = freq_table[soc_opp_count - 1].frequency;

I think soc_opp_count includes all OPPs from the DT, some of which might
be disabled based on the fuse settings of the SoC. So this should
probably not switch to the highest OPP unconditionally, but rather
switch to the highest _enabled_ OPP.

Regards,
Lucas
 
>  	return cpufreq_generic_init(policy, freq_table, transition_latency);
>  }
>  
> @@ -173,6 +174,7 @@ static struct cpufreq_driver imx6q_cpufreq_driver = {
>  	.init = imx6q_cpufreq_init,
>  	.name = "imx6q-cpufreq",
>  	.attr = cpufreq_generic_attr,
> +	.suspend = cpufreq_generic_suspend,
>  };
>  
>  static int imx6q_cpufreq_probe(struct platform_device *pdev)
Leonard Crestez April 4, 2017, 5:04 p.m. UTC | #2
On Tue, 2017-04-04 at 11:51 +0200, Lucas Stach wrote:
> Am Freitag, den 31.03.2017, 22:25 +0300 schrieb Leonard Crestez:
> > 
> > If the cpufreq driver tries to modify voltage/freq during suspend/resume
> > it might need to control an external PMIC via I2C or SPI but those
> > devices might be already suspended.
> > 
> > To avoid this scenario we just increase cpufreq to highest setpoint
> > before suspend. This issue can easily be triggered by ldo-bypass but in
> > theory any regulator set_voltage call can end up having to modify
> > external supply voltages.
> > 
> > Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> > Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
> > ---
> >  drivers/cpufreq/imx6q-cpufreq.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
> > index be90ee3..e2c1fbf 100644
> > --- a/drivers/cpufreq/imx6q-cpufreq.c
> > +++ b/drivers/cpufreq/imx6q-cpufreq.c
> > @@ -162,6 +162,7 @@ static int imx6q_set_target(struct cpufreq_policy *policy, unsigned int index)
> >  static int imx6q_cpufreq_init(struct cpufreq_policy *policy)
> >  {
> >  	policy->clk = arm_clk;
> > +	policy->suspend_freq = freq_table[soc_opp_count - 1].frequency;
> I think soc_opp_count includes all OPPs from the DT, some of which might
> be disabled based on the fuse settings of the SoC. So this should
> probably not switch to the highest OPP unconditionally, but rather
> switch to the highest _enabled_ OPP.

You're right, this does not appear to be correct. Looking at
soc_opp_count it should probably be a local variable in the code
initializing imx6_soc_volt. And the imx6_soc_volt array itself could
now be replaced with opp's support for multiple supply voltages.

I'll post v2.
diff mbox

Patch

diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
index be90ee3..e2c1fbf 100644
--- a/drivers/cpufreq/imx6q-cpufreq.c
+++ b/drivers/cpufreq/imx6q-cpufreq.c
@@ -162,6 +162,7 @@  static int imx6q_set_target(struct cpufreq_policy *policy, unsigned int index)
 static int imx6q_cpufreq_init(struct cpufreq_policy *policy)
 {
 	policy->clk = arm_clk;
+	policy->suspend_freq = freq_table[soc_opp_count - 1].frequency;
 	return cpufreq_generic_init(policy, freq_table, transition_latency);
 }
 
@@ -173,6 +174,7 @@  static struct cpufreq_driver imx6q_cpufreq_driver = {
 	.init = imx6q_cpufreq_init,
 	.name = "imx6q-cpufreq",
 	.attr = cpufreq_generic_attr,
+	.suspend = cpufreq_generic_suspend,
 };
 
 static int imx6q_cpufreq_probe(struct platform_device *pdev)