From: Dong Aisheng <dongas86@gmail.com>
To: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chanwoo Choi <cwchoi00@gmail.com>,
Dong Aisheng <aisheng.dong@nxp.com>,
Linux PM <linux-pm@vger.kernel.org>,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>,
Sascha Hauer <kernel@pengutronix.de>,
Shawn Guo <shawnguo@kernel.org>, dl-linux-imx <linux-imx@nxp.com>,
open list <linux-kernel@vger.kernel.org>,
myungjoo.ham@samsung.com, kyungmin.park@samsung.com,
Abel Vesa <abel.vesa@nxp.com>
Subject: Re: [PATCH 07/11] PM / devfreq: check get_dev_status before start monitor
Date: Fri, 12 Mar 2021 18:57:14 +0800 [thread overview]
Message-ID: <CAA+hA=Q0M0bTf0VLjNmf23HqFn4Unk0h4BN-mEQXb1LkZLV=NQ@mail.gmail.com> (raw)
In-Reply-To: <b5a3ee55-0c71-a0ca-b03f-3b6790f3d2f4@samsung.com>
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.
> 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
next prev parent reply other threads:[~2021-03-12 10:58 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-09 12:58 [PATCH 00/11] PM / devfreq: a few small fixes and improvements Dong Aisheng
2021-03-09 12:58 ` [PATCH 01/11] doc: ABI: devfreq: remove invalid central_polling description Dong Aisheng
2021-03-09 15:01 ` Chanwoo Choi
2021-03-09 12:58 ` [PATCH 02/11] PM / devfreq: remove the invalid description for get_target_freq Dong Aisheng
2021-03-09 15:02 ` Chanwoo Choi
2021-03-09 15:14 ` Dong Aisheng
2021-03-09 12:58 ` [PATCH 03/11] PM / devfreq: fix the wrong set_freq path for userspace governor Dong Aisheng
2021-03-09 15:13 ` Chanwoo Choi
2021-03-09 15:16 ` Dong Aisheng
2021-03-09 12:58 ` [PATCH 04/11] PM / devfreq: bail out early if no freq changes in devfreq_set_target Dong Aisheng
2021-03-09 15:47 ` Chanwoo Choi
2021-03-10 2:42 ` Dong Aisheng
2021-03-09 12:58 ` [PATCH 05/11] PM / devfreq: use more accurate returned new_freq as resume_freq Dong Aisheng
2021-03-09 15:53 ` Chanwoo Choi
2021-03-10 2:43 ` Dong Aisheng
2021-03-10 3:07 ` Chanwoo Choi
2021-03-10 3:04 ` Dong Aisheng
2021-03-09 12:58 ` [PATCH 06/11] PM / devfreq: drop the unnecessary low variable initialization Dong Aisheng
2021-03-09 12:58 ` [PATCH 07/11] PM / devfreq: check get_dev_status before start monitor Dong Aisheng
2021-03-09 15:58 ` Chanwoo Choi
2021-03-09 16:12 ` Chanwoo Choi
2021-03-10 2:56 ` Dong Aisheng
2021-03-10 3:25 ` Chanwoo Choi
2021-03-10 4:56 ` Dong Aisheng
2021-03-11 7:10 ` Chanwoo Choi
2021-03-12 10:57 ` Dong Aisheng [this message]
2021-03-12 16:09 ` Chanwoo Choi
2021-03-13 6:45 ` Dong Aisheng
2021-03-18 8:03 ` Dong Aisheng
2021-03-18 9:54 ` Chanwoo Choi
2021-03-18 9:59 ` Chanwoo Choi
2021-03-18 10:51 ` Dong Aisheng
2021-03-10 2:51 ` Dong Aisheng
2021-03-09 12:58 ` [PATCH 08/11] PM / devfreq: check get_dev_status in devfreq_update_stats Dong Aisheng
2021-03-09 16:02 ` Chanwoo Choi
2021-03-09 16:20 ` Chanwoo Choi
2021-03-10 3:00 ` Dong Aisheng
2021-03-11 7:01 ` Chanwoo Choi
2021-03-09 12:58 ` [PATCH 09/11] PM / devfreq: governor: optimize simpleondemand get_target_freq Dong Aisheng
2021-03-09 16:09 ` Chanwoo Choi
2021-03-10 3:02 ` Dong Aisheng
2021-03-09 12:58 ` [PATCH 10/11] PM / devfreq: imx8m-ddrc: remove imx8m_ddrc_get_dev_status Dong Aisheng
2021-03-09 16:22 ` Chanwoo Choi
2021-03-09 12:58 ` [PATCH 11/11] PM / devfreq: imx8m-ddrc: drop polling_ms Dong Aisheng
2021-03-09 16:23 ` Chanwoo Choi
2021-03-10 3:03 ` Dong Aisheng
2021-03-09 12:58 ` [PATCH 00/11] PM / devfreq: a few small fixes and improvements Dong Aisheng
2021-03-09 12:58 ` [PATCH 01/11] doc: ABI: devfreq: remove invalid central_polling description Dong Aisheng
2021-03-09 12:58 ` [PATCH 02/11] PM / devfreq: remove the invalid description for get_target_freq Dong Aisheng
2021-03-09 12:58 ` [PATCH 03/11] PM / devfreq: fix the wrong set_freq path for userspace governor Dong Aisheng
2021-03-09 12:58 ` [PATCH 04/11] PM / devfreq: bail out early if no freq changes in devfreq_set_target Dong Aisheng
2021-03-09 12:58 ` [PATCH 05/11] PM / devfreq: use more accurate returned new_freq as resume_freq Dong Aisheng
2021-03-09 12:58 ` [PATCH 06/11] PM / devfreq: drop the unnecessary low variable initialization Dong Aisheng
2021-03-09 12:58 ` [PATCH 07/11] PM / devfreq: check get_dev_status before start monitor Dong Aisheng
2021-03-09 12:58 ` [PATCH 08/11] PM / devfreq: check get_dev_status in devfreq_update_stats Dong Aisheng
2021-03-09 12:58 ` [PATCH 09/11] PM / devfreq: governor: optimize simpleondemand get_target_freq Dong Aisheng
2021-03-09 12:58 ` [PATCH 10/11] PM / devfreq: imx8m-ddrc: remove imx8m_ddrc_get_dev_status Dong Aisheng
2021-03-09 12:58 ` [PATCH 11/11] PM / devfreq: imx8m-ddrc: drop polling_ms Dong Aisheng
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