From: Lukasz Luba <l.luba@partner.samsung.com>
To: Chanwoo Choi <cw00.choi@samsung.com>,
linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pm@vger.kernel.org, devicetree@vger.kernel.org
Cc: tjakobi@math.uni-bielefeld.de, myungjoo.ham@samsung.com,
kyungmin.park@samsung.com, rjw@rjwysocki.net,
len.brown@intel.com, pavel@ucw.cz, gregkh@linuxfoundation.org,
keescook@chromium.org, anton@enomsg.org, ccross@android.com,
tony.luck@intel.com, robh+dt@kernel.org, mark.rutland@arm.com,
kgene@kernel.org, krzk@kernel.org, m.szyprowski@samsung.com,
b.zolnierkie@samsung.com
Subject: Re: [PATCH 3/6] devfreq: add support for suspend/resume of a devfreq device
Date: Mon, 3 Dec 2018 15:05:10 +0100 [thread overview]
Message-ID: <1aaf315b-f262-dad1-0e82-548410d10b5e@partner.samsung.com> (raw)
In-Reply-To: <5BFB3C17.40502@samsung.com>
Hi Chanwoo Choi,
On 11/26/18 1:19 AM, Chanwoo Choi wrote:
> Hi Lukasz,
>
> I add the one more comment for devfreq_resume_device()
>
> On 2018년 11월 23일 19:01, Lukasz Luba wrote:
>> Hi Chanwoo Choi,
>>
>> On 11/23/18 12:54 AM, Chanwoo Choi wrote:
>>> Hi Lukasz,
>>>
>>> I add one more comment about devfreq_resume_device().
>>>
>>> On 2018년 11월 22일 20:00, Lukasz Luba wrote:
>>>>
>>>>
>>>> On 11/22/18 3:58 AM, Chanwoo Choi wrote:
>>>>> On 2018년 11월 22일 03:01, Lukasz Luba wrote:
>>>>>> The patch adds support for handling suspend/resume process.
>>>>>> It uses atomic variables to make sure no race condition
>>>>>> affects the process.
>>>>>>
>>>>>> The patch draws on Tobias Jakobi's work posted ~2 years ago, who tried to
>>>>>> solve issue with devfreq device's frequency during suspend/resume.
>>>>>> During the discussion on LKML some corner cases and comments appeared
>>>>>> related to the design. This patch address them keeping in mind suggestions
>>>>>> from Chanwoo Choi.
>>>>>
>>>>> Please remove the duplicate information about patch history.
>>>>>
>>>>>>
>>>>>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>>>>>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>>>>>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>>>>>> ---
>>>>>> drivers/devfreq/devfreq.c | 45 +++++++++++++++++++++++++++++++++++++++------
>>>>>> 1 file changed, 39 insertions(+), 6 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>>>>> index cf9c643..7e09de8 100644
>>>>>> --- a/drivers/devfreq/devfreq.c
>>>>>> +++ b/drivers/devfreq/devfreq.c
>>>>>> @@ -872,14 +872,33 @@ EXPORT_SYMBOL(devm_devfreq_remove_device);
>>>>>> */
>>>>>> int devfreq_suspend_device(struct devfreq *devfreq)
>>>>>> {
>>>>>> - if (!devfreq)
>>>>>> - return -EINVAL;
>>>>>> + int ret;
>>>>>
>>>>> Move 'ret' definition under 'if (devfreq->suspend_freq) {'
>>>>> because 'ret' is used if suspend_freq isn't zero.
>>>> Not only there, 6 lines above 'ret' is used for
>>>> devfreq->governor->event_handler().
>>>
>>> OK.
>>>
>>>>>
>>>>>> + unsigned long prev_freq;
>>>>>> + u32 flags = 0;
>>>>>> +
>>>>>> + if (!devfreq)
>>>>>> + return -EINVAL;
>>>>>> +
>>>>>> + if (devfreq->governor) {
>>>>>> + ret = devfreq->governor->event_handler(devfreq,
>>>>>> + DEVFREQ_GOV_SUSPEND, NULL);
>>>>>> + if (ret)
>>>>>> + return ret;
>>>>>> + }
>>>>>>
>>>>>> - if (!devfreq->governor)
>>>>>> - return 0;
>>>>>> + if (devfreq->suspend_freq) {
>>>>>> + if (atomic_inc_return(&devfreq->suspend_count) > 1)
>>>>>> + return 0;
>>>>>>
>>>>>> - return devfreq->governor->event_handler(devfreq,
>>>>>> - DEVFREQ_GOV_SUSPEND, NULL);
>>>>>> + ret = devfreq_set_target(devfreq, devfreq->suspend_freq,
>>>>>> + &prev_freq, flags);
>>>>>
>>>>> Remove the 'prev_freq' parameter.
>>>> OK
>>>>>
>>>>>> + if (ret)
>>>>>> + return ret;
>>>>>> +
>>>>>> + devfreq->resume_freq = prev_freq;
>>>>>
>>>>> As I commented on patch2, if devfreq_set_taget save the current frequency
>>>>> to 'devfreq->resume_freq', this line is not needed.
>>>> OK
>>>>>
>>>>>
>>>>>> + }
>>>>>> +
>>>>>> + return 0;
>>>>>> }
>>>>>> EXPORT_SYMBOL(devfreq_suspend_device);
>>>>>>
>>>>>> @@ -893,9 +912,23 @@ EXPORT_SYMBOL(devfreq_suspend_device);
>>>>>> */
>>>>>> int devfreq_resume_device(struct devfreq *devfreq)
>>>>>> {
>>>>>> + int ret;
>>>>>
>>>>> Move 'ret' definition under 'if (devfreq->suspend_freq) {'
>>>>> because 'ret' is used if suspend_freq isn't zero.
>>>> OK
>>>
>>> If you change the devfreq_resume_device() according to my new comment,
>>> please ignore it.
>>>
>>>>>
>>>>>> + unsigned long prev_freq;
>>>>>
>>>>> Remove prev_freq variable which is not used on this function.
>>>>> After calling devfreq_set_target, prev_freq is not used.
>>>> OK
>>>>>
>>>>>> + u32 flags = 0;
>>>>>> +
>>>>>> if (!devfreq)
>>>>>> return -EINVAL;
>>>>>>
>>>>>> + if (devfreq->suspend_freq) {
>
> In devfreq_resume_device(), it should check the 'devfreq->resume_freq'
> instead of 'devfreq->suspend_freq'.
OK, I will fix it.
Regards,
Lukasz
>
>
>>>>>> + if (atomic_dec_return(&devfreq->suspend_count) >= 1)
>>>>>> + return 0;
>>>>>> +
>>>>>> + ret = devfreq_set_target(devfreq, devfreq->resume_freq,
>>>>>> + &prev_freq, flags);
>>>>>
>>>>> Remove the 'prev_freq' parameter.
>>>> OK
>>>>>
>>>>>> + if (ret)
>>>>>> + return ret;
>>>>>> + }
>>>>>> +
>>>>>> if (!devfreq->governor)
>>>>>> return 0;
>>>
>>> Please change the code as following because you uses the following type
>>> in the devfreq_suspend_device(). If there is any special issue, please
>>> keep the same format in order to improve the readability.
>>>
>>> if (devfreq->governor) {
>>> ret = devfreq->governor->event_handler(devfreq,
>>> DEVFREQ_GOV_RESUME, NULL);
>>> if (ret)
>>> return ret;
>>> }
>>>
>>>
>> OK, I will change the code to keep the same format.
>> Thank you for the review.
>>
>> Regards,
>> Lukasz
>>
>>
>>
>
>
next prev parent reply other threads:[~2018-12-03 14:05 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20181121180156eucas1p225af7f4341a039264ff26f2a9ad9bb12@eucas1p2.samsung.com>
2018-11-21 18:01 ` [PATCH 0/6] devfreq: handle suspend/resume Lukasz Luba
[not found] ` <CGME20181121180201eucas1p1f1f96941c3d16a96722e65d5c21bfe80@eucas1p1.samsung.com>
2018-11-21 18:01 ` [PATCH 1/6] devfreq: add basic fileds supporting suspend functionality Lukasz Luba
2018-11-22 2:37 ` Chanwoo Choi
[not found] ` <CGME20181121180202eucas1p27d3aa58411abeae03181c38b91fc67de@eucas1p2.samsung.com>
2018-11-21 18:01 ` [PATCH 2/6] devfreq: refactor set_target frequency function Lukasz Luba
2018-11-22 2:52 ` Chanwoo Choi
2018-11-22 2:54 ` Chanwoo Choi
2018-11-22 10:40 ` Lukasz Luba
2018-11-22 23:45 ` Chanwoo Choi
2018-11-23 9:58 ` Lukasz Luba
[not found] ` <CGME20181121180204eucas1p1c5891d498aa59c0e10dd3ba4727a4382@eucas1p1.samsung.com>
2018-11-21 18:01 ` [PATCH 3/6] devfreq: add support for suspend/resume of a devfreq device Lukasz Luba
2018-11-22 2:58 ` Chanwoo Choi
2018-11-22 11:00 ` Lukasz Luba
2018-11-22 23:54 ` Chanwoo Choi
2018-11-23 10:01 ` Lukasz Luba
2018-11-26 0:19 ` Chanwoo Choi
2018-12-03 14:05 ` Lukasz Luba [this message]
[not found] ` <CGME20181121180205eucas1p1dc52369476400cd07058d232bd8dbcd7@eucas1p1.samsung.com>
2018-11-21 18:01 ` [PATCH 4/6] devfreq: add devfreq_suspend/resume() functions Lukasz Luba
2018-11-22 3:07 ` Chanwoo Choi
2018-11-22 11:02 ` Lukasz Luba
[not found] ` <CGME20181121180206eucas1p265865226e3938a28e842e8367233dc2e@eucas1p2.samsung.com>
2018-11-21 18:01 ` [PATCH 5/6] drivers: power: suspend: call devfreq suspend/resume Lukasz Luba
2018-11-22 3:08 ` Chanwoo Choi
[not found] ` <CGME20181121180208eucas1p11482a783ab1b1bceb8c9f6a1f50682c3@eucas1p1.samsung.com>
2018-11-21 18:01 ` [PATCH 6/6] arm: dts: exynos4: set opp-suspend for DMC and leftbus Lukasz Luba
2018-11-22 3:09 ` Chanwoo Choi
2018-11-22 11:04 ` Lukasz Luba
2018-11-22 17:24 ` [PATCH 0/6] devfreq: handle suspend/resume Tobias Jakobi
2018-11-22 17:44 ` Lukasz Luba
[not found] ` <CGME20181121180201eucas1p1f1f96941c3d16a96722e65d5c21bfe80@epcms1p8>
2018-11-26 8:14 ` [PATCH 1/6] devfreq: add basic fileds supporting suspend functionality MyungJoo Ham
2018-12-03 14:03 ` Lukasz Luba
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1aaf315b-f262-dad1-0e82-548410d10b5e@partner.samsung.com \
--to=l.luba@partner.samsung.com \
--cc=anton@enomsg.org \
--cc=b.zolnierkie@samsung.com \
--cc=ccross@android.com \
--cc=cw00.choi@samsung.com \
--cc=devicetree@vger.kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=keescook@chromium.org \
--cc=kgene@kernel.org \
--cc=krzk@kernel.org \
--cc=kyungmin.park@samsung.com \
--cc=len.brown@intel.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=linux-samsung-soc@vger.kernel.org \
--cc=m.szyprowski@samsung.com \
--cc=mark.rutland@arm.com \
--cc=myungjoo.ham@samsung.com \
--cc=pavel@ucw.cz \
--cc=rjw@rjwysocki.net \
--cc=robh+dt@kernel.org \
--cc=tjakobi@math.uni-bielefeld.de \
--cc=tony.luck@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).