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 <tjak...@math.uni-bielefeld.de>
>> Suggested-by: Chanwoo Choi <cw00.c...@samsung.com>
>> Signed-off-by: Lukasz Luba <l.l...@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().
>
>> + 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
>
>> + 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) {
>> + 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;
>>
>>
>
>
Regards,
Lukasz Luba
