From: Chanwoo Choi <cwchoi00@gmail.com>
To: Dong Aisheng <dongas86@gmail.com>, Chanwoo Choi <cw00.choi@samsung.com>
Cc: 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: Sat, 13 Mar 2021 01:09:51 +0900 [thread overview]
Message-ID: <d92b7660-a622-06f3-6e1f-03c99fdf0a55@gmail.com> (raw)
In-Reply-To: <CAA+hA=Q0M0bTf0VLjNmf23HqFn4Unk0h4BN-mEQXb1LkZLV=NQ@mail.gmail.com>
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.
>
>> 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
next prev parent reply other threads:[~2021-03-12 16:10 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
2021-03-12 16:09 ` Chanwoo Choi [this message]
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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