| Message ID | 1479909087-22659-3-git-send-email-tjakobi@math.uni-bielefeld.de (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
Hi Tobias, Looks good to me. Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com> Best Regards, Chanwoo Choi On 2016년 11월 23일 22:51, Tobias Jakobi wrote: > On the Exynos4412 SoC the DevFreq subsystem adjusts frequency > of the various internal busses and corresponding voltages. > > E.g. the clock of the DMC (dynamic memory controller) bus > together with the voltage of the MIF regulator are controlled > by this. > > If DMC activity is low and DevFreq has set a lower OPP, the > following can happen. > > If the system is restarted or goes into a suspend/resume-cycle, > the first-stage (BL0) bootloader takes over, which also > initializes clocks to default values. Since the PMIC is an > external component and not part of the SoC, the BL0 doesn't > set any default voltages. Upon setting the default clocks > for the DMC bus, the BL0 hangs because the corresponding > voltage is too low. > > To fix this, we make sure to only go into suspend with a 'safe' > DevFreq configuration. > > Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de> > --- > drivers/base/power/main.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c > index 5a94dfa..9cd7e06 100644 > --- a/drivers/base/power/main.c > +++ b/drivers/base/power/main.c > @@ -32,6 +32,7 @@ > #include <trace/events/power.h> > #include <linux/cpufreq.h> > #include <linux/cpuidle.h> > +#include <linux/devfreq.h> > #include <linux/timer.h> > > #include "../base.h" > @@ -943,6 +944,7 @@ void dpm_resume(pm_message_t state) > dpm_show_time(starttime, state, NULL); > > cpufreq_resume(); > + devfreq_resume(); > trace_suspend_resume(TPS("dpm_resume"), state.event, false); > } > > @@ -1582,6 +1584,7 @@ int dpm_suspend(pm_message_t state) > trace_suspend_resume(TPS("dpm_suspend"), state.event, true); > might_sleep(); > > + devfreq_suspend(); > cpufreq_suspend(); > > mutex_lock(&dpm_list_mtx); > -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index 5a94dfa..9cd7e06 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -32,6 +32,7 @@ #include <trace/events/power.h> #include <linux/cpufreq.h> #include <linux/cpuidle.h> +#include <linux/devfreq.h> #include <linux/timer.h> #include "../base.h" @@ -943,6 +944,7 @@ void dpm_resume(pm_message_t state) dpm_show_time(starttime, state, NULL); cpufreq_resume(); + devfreq_resume(); trace_suspend_resume(TPS("dpm_resume"), state.event, false); } @@ -1582,6 +1584,7 @@ int dpm_suspend(pm_message_t state) trace_suspend_resume(TPS("dpm_suspend"), state.event, true); might_sleep(); + devfreq_suspend(); cpufreq_suspend(); mutex_lock(&dpm_list_mtx);
On the Exynos4412 SoC the DevFreq subsystem adjusts frequency of the various internal busses and corresponding voltages. E.g. the clock of the DMC (dynamic memory controller) bus together with the voltage of the MIF regulator are controlled by this. If DMC activity is low and DevFreq has set a lower OPP, the following can happen. If the system is restarted or goes into a suspend/resume-cycle, the first-stage (BL0) bootloader takes over, which also initializes clocks to default values. Since the PMIC is an external component and not part of the SoC, the BL0 doesn't set any default voltages. Upon setting the default clocks for the DMC bus, the BL0 hangs because the corresponding voltage is too low. To fix this, we make sure to only go into suspend with a 'safe' DevFreq configuration. Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de> --- drivers/base/power/main.c | 3 +++ 1 file changed, 3 insertions(+)