Messages in this thread | | | From | Dong Aisheng <> | Date | Thu, 18 Mar 2021 18:51:50 +0800 | Subject | Re: [PATCH 07/11] PM / devfreq: check get_dev_status before start monitor |
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On Thu, Mar 18, 2021 at 5:42 PM Chanwoo Choi <cw00.choi@samsung.com> wrote: > > On 3/18/21 6:54 PM, Chanwoo Choi wrote: > > On 3/18/21 5:03 PM, Dong Aisheng wrote: > >> Hi Chanwoo, > >> > >> On Sat, Mar 13, 2021 at 2:45 PM Dong Aisheng <dongas86@gmail.com> wrote: > >>> > >>> On Sat, Mar 13, 2021 at 12:09 AM Chanwoo Choi <cwchoi00@gmail.com> wrote: > >>>> > >>>> On 21. 3. 12. 오후 7:57, Dong Aisheng wrote: > >>>>> On Thu, Mar 11, 2021 at 2:54 PM Chanwoo Choi <cw00.choi@samsung.com> wrote: > >>>>>> > >>>>>> On 3/10/21 1:56 PM, Dong Aisheng wrote: > >>>>>>> On Wed, Mar 10, 2021 at 11:08 AM Chanwoo Choi <cw00.choi@samsung.com> wrote: > >>>>>>>> > >>>>>>>> On 3/10/21 11:56 AM, Dong Aisheng wrote: > >>>>>>>>> On Wed, Mar 10, 2021 at 12:12 AM Chanwoo Choi <cwchoi00@gmail.com> wrote: > >>>>>>>>>> > >>>>>>>>>> On 21. 3. 10. 오전 12:58, Chanwoo Choi wrote: > >>>>>>>>>>> On 21. 3. 9. 오후 9:58, Dong Aisheng wrote: > >>>>>>>>>>>> The devfreq monitor depends on the device to provide load information > >>>>>>>>>>>> by .get_dev_status() to calculate the next target freq. > >>>>>>>>>>>> > >>>>>>>>>>>> And this will cause changing governor to simple ondemand fail > >>>>>>>>>>>> if device can't support. > >>>>>>>>>>>> > >>>>>>>>>>>> Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com> > >>>>>>>>>>>> --- > >>>>>>>>>>>> drivers/devfreq/devfreq.c | 10 +++++++--- > >>>>>>>>>>>> drivers/devfreq/governor.h | 2 +- > >>>>>>>>>>>> drivers/devfreq/governor_simpleondemand.c | 3 +-- > >>>>>>>>>>>> 3 files changed, 9 insertions(+), 6 deletions(-) > >>>>>>>>>>>> > >>>>>>>>>>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c > >>>>>>>>>>>> index 7231fe6862a2..d1787b6c7d7c 100644 > >>>>>>>>>>>> --- a/drivers/devfreq/devfreq.c > >>>>>>>>>>>> +++ b/drivers/devfreq/devfreq.c > >>>>>>>>>>>> @@ -482,10 +482,13 @@ static void devfreq_monitor(struct work_struct > >>>>>>>>>>>> *work) > >>>>>>>>>>>> * to be called from governor in response to DEVFREQ_GOV_START > >>>>>>>>>>>> * event when device is added to devfreq framework. > >>>>>>>>>>>> */ > >>>>>>>>>>>> -void devfreq_monitor_start(struct devfreq *devfreq) > >>>>>>>>>>>> +int devfreq_monitor_start(struct devfreq *devfreq) > >>>>>>>>>>>> { > >>>>>>>>>>>> if (IS_SUPPORTED_FLAG(devfreq->governor->flags, IRQ_DRIVEN)) > >>>>>>>>>>>> - return; > >>>>>>>>>>>> + return 0; > >>>>>>>>>>>> + > >>>>>>>>>>>> + if (!devfreq->profile->get_dev_status) > >>>>>>>>>>>> + return -EINVAL; > >>>>>>>>>> > >>>>>>>>>> Again, I think that get_dev_status is not used for all governors. > >>>>>>>>>> So that it cause the governor start fail. Don't check whether > >>>>>>>>>> .get_dev_status is NULL or not. > >>>>>>>>>> > >>>>>>>>> > >>>>>>>>> I'm not quite understand your point. > >>>>>>>>> it is used by governor_simpleondemand.c and tegra_devfreq_governor. > >>>>>>>>> get_target_freq -> devfreq_update_stats -> get_dev_status > >>>>>>>> > >>>>>>>> The devfreq can add the new governor by anyone. > >>>>>>>> So these functions like devfreq_monitor_* have to support > >>>>>>>> the governors and also must support the governor to be added > >>>>>>>> in the future. > >>>>>>> > >>>>>>> Yes, but devfreq_monitor_* is only used by polling mode, right? > >>>>>>> The governor using it has to implement get_dev_status unless > >>>>>>> there's an exception in the future. > >>>>>>> > >>>>>>> Currently this patch wants to address the issue that user can switch > >>>>>>> to ondemand governor (polling mode) by sysfs even devices does > >>>>>>> not support it (no get_dev_status implemented). > >>>>>> > >>>>>> As I commented, I'll fix this issue. If devfreq driver doesn't implement > >>>>>> the .get_dev_status, don't show it via available_governors. I think that > >>>>>> it is fundamental solution to fix this issue. > >>>>> > >>>>> Sounds good > >>>>> > >>>>>> So on this version, > >>>>>> don't add the this conditional statement on this function > >>>>>> > >>>>> > >>>>> Almost all this patch did is adding a checking for get_dev_status. > >>>>> So do you mean drop this patch? > >>>>> I wonder it's still a necessary checking to explicitly tell devfreq monitor > >>>>> users that get_dev_status is needed during governor startup. > >>>> > >>>> I think that the it is enough to check .get_dev_status in > >>>> devfreq_update_stats. We have to check it on where it is used. > >>>> > >>> > >>> I think the drawback of only checking .get_dev_status in > >>> devfreq_update_stats is: > >>> 1. devfreq will still register successfully and ondemand governor starts ok > >>> 2. ondemand governor will still be shown in sysfs which is something > >>> you want to fix > >>> 3. devfreq will end up printing endless error messages in devfreq_monitor worker > >>> "dvfs failed with (%d) error" as the possible missing .get_dev_status > > > > I think that devfreq_monitor_start have to handle only work instance. > > This approach is too considering the deep check list. > > I want to resolve this periodical error log with different solution. > > > > Actually, we have to reject the registration of devfreq device > > when calling devfreq_add_device instead of checking .get_dev_status > > in devfreq_monitor_start(). > > > I'll reject the registration of devfreq device if the mandatory > function pointer of struct devfreq_dev_profile are not initialized. > - .get_dev_status > If some governors like simple_ondemand, have to initialize it. > So, I need to add the new flag to specify this feature. > - .target is mandatory for all devfreq devices. I'll check it.
Okay, thanks Then i will drop this patch and resend series with your other comments addressed.
Regards Aisheng
> > > > > > >>> > >>> So i wonder if you don't like changing the common devfreq_monitor_start in order > >>> to make it look common for all governors, then we probably still need > >>> to fix it in > >>> ondemand governor in order to avoid the possible above issues. > >>> > >>> static int devfreq_simple_ondemand_handler(struct devfreq *devfreq, > >>> unsigned int event, void *data) > >>> { > >>> switch (event) { > >>> case DEVFREQ_GOV_START: > >>> if (!devfreq->profile->get_dev_status) > >>> return -EINVAL; > >>> > >>> return devfreq_monitor_start(devfreq); > >>> ... > >>> } > >>> > >>> How do you think? > >> > >> Any feedback? > >> > >> I'm waiting for your confirmation whether dropping this one, > >> then I can re-sent the series. > >> > >> Regards > >> Aisheng > >> > >>> > >>> Regards > >>> Aisheng > >>> > >>> > >>>>> > >>>>>> And on next version, please use the capital letter for first character > >>>>>> on patch title as following: > >>>>>> > >>>>>> - PM / devfreq: Check get_dev_status before start monitor > >>>>>> > >>>>> > >>>>> Okay to me. > >>>>> Thanks for the suggestion. > >>>>> > >>>>> Regards > >>>>> Aisheng > >>>>> > >>>>>>> > >>>>>>> Regards > >>>>>>> Aisheng > >>>>>>> > >>>>>>>> > >>>>>>>>> > >>>>>>>>> Without checking, device can switch to ondemand governor if it does not support. > >>>>>>>>> > >>>>>>>>> Am i missed something? > >>>>>>>>> > >>>>>>>>> Regards > >>>>>>>>> Aisheng > >>>>>>>>> > >>>>>>>>>>>> switch (devfreq->profile->timer) { > >>>>>>>>>>>> case DEVFREQ_TIMER_DEFERRABLE: > >>>>>>>>>>>> @@ -495,12 +498,13 @@ void devfreq_monitor_start(struct devfreq *devfreq) > >>>>>>>>>>>> INIT_DELAYED_WORK(&devfreq->work, devfreq_monitor); > >>>>>>>>>>>> break; > >>>>>>>>>>>> default: > >>>>>>>>>>>> - return; > >>>>>>>>>>>> + return -EINVAL; > >>>>>>>>>>>> } > >>>>>>>>>>>> if (devfreq->profile->polling_ms) > >>>>>>>>>>>> queue_delayed_work(devfreq_wq, &devfreq->work, > >>>>>>>>>>>> msecs_to_jiffies(devfreq->profile->polling_ms)); > >>>>>>>>>>>> + return 0; > >>>>>>>>>>>> } > >>>>>>>>>>>> EXPORT_SYMBOL(devfreq_monitor_start); > >>>>>>>>>>>> diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h > >>>>>>>>>>>> index 5cee3f64fe2b..31af6d072a10 100644 > >>>>>>>>>>>> --- a/drivers/devfreq/governor.h > >>>>>>>>>>>> +++ b/drivers/devfreq/governor.h > >>>>>>>>>>>> @@ -75,7 +75,7 @@ struct devfreq_governor { > >>>>>>>>>>>> unsigned int event, void *data); > >>>>>>>>>>>> }; > >>>>>>>>>>>> -void devfreq_monitor_start(struct devfreq *devfreq); > >>>>>>>>>>>> +int devfreq_monitor_start(struct devfreq *devfreq); > >>>>>>>>>>>> void devfreq_monitor_stop(struct devfreq *devfreq); > >>>>>>>>>>>> void devfreq_monitor_suspend(struct devfreq *devfreq); > >>>>>>>>>>>> void devfreq_monitor_resume(struct devfreq *devfreq); > >>>>>>>>>>>> diff --git a/drivers/devfreq/governor_simpleondemand.c > >>>>>>>>>>>> b/drivers/devfreq/governor_simpleondemand.c > >>>>>>>>>>>> index d57b82a2b570..ea287b57cbf3 100644 > >>>>>>>>>>>> --- a/drivers/devfreq/governor_simpleondemand.c > >>>>>>>>>>>> +++ b/drivers/devfreq/governor_simpleondemand.c > >>>>>>>>>>>> @@ -89,8 +89,7 @@ static int devfreq_simple_ondemand_handler(struct > >>>>>>>>>>>> devfreq *devfreq, > >>>>>>>>>>>> { > >>>>>>>>>>>> switch (event) { > >>>>>>>>>>>> case DEVFREQ_GOV_START: > >>>>>>>>>>>> - devfreq_monitor_start(devfreq); > >>>>>>>>>>>> - break; > >>>>>>>>>>>> + return devfreq_monitor_start(devfreq); > >>>>>>>>>>>> case DEVFREQ_GOV_STOP: > >>>>>>>>>>>> devfreq_monitor_stop(devfreq); > >>>>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>>> Need to handle the all points of devfreq_monitor_start() usage. > >>>>>>>>>>> please check the tegra30-devfreq.c for this update. > >>>>>>>>>>> > >>>>>>>>>>> $ grep -rn "devfreq_monitor_start" drivers/ > >>>>>>>>>>> drivers/devfreq/governor_simpleondemand.c:92: > >>>>>>>>>>> devfreq_monitor_start(devfreq); > >>>>>>>>>>> drivers/devfreq/tegra30-devfreq.c:744: > >>>>>>>>>>> devfreq_monitor_start(devfreq); > >>>>>>>>>>> ...... > >>>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> -- > >>>>>>>>>> Best Regards, > >>>>>>>>>> Samsung Electronics > >>>>>>>>>> Chanwoo Choi > >>>>>>>>> > >>>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> -- > >>>>>>>> Best Regards, > >>>>>>>> Chanwoo Choi > >>>>>>>> Samsung Electronics > >>>>>>> > >>>>>>> > >>>>>> > >>>>>> > >>>>>> -- > >>>>>> Best Regards, > >>>>>> Chanwoo Choi > >>>>>> Samsung Electronics > >>>> > >>>> > >>>> -- > >>>> Best Regards, > >>>> Samsung Electronics > >>>> Chanwoo Choi > >> > >> > > > > > > > -- > Best Regards, > Chanwoo Choi > Samsung Electronics
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