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    SubjectRe: [PATCH v2 2/5] devfreq: add support for suspend/resume of a devfreq device
    Hi,

    On 2018년 12월 04일 14:36, Chanwoo Choi wrote:
    > Hi Lukasz,
    >
    > Looks good to me. But, I add the some comments.
    > If you will fix it, feel free to add my tag:
    > Reviewed-by: Chanwoo choi <cw00.choi@samsung.com>

    Sorry. Fix typo 'choi' to 'Choi' as following.
    Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>

    >
    > On 2018년 12월 03일 23:31, Lukasz Luba wrote:
    >> The patch prepares devfreq device for handling suspend/resume
    >> functionality. The new fields will store needed information during this
    >
    > nitpick. Remove unneeded space. There are two spaces between '.' and 'The new'.
    >
    >> process. Devfreq framework handles opp-suspend DT entry and there is no
    >
    > ditto.
    >
    >> need of modyfications in the drivers code. It uses atomic variables to
    >
    > ditto.
    >
    >> make sure no race condition affects the process.
    >>
    >> The patch is based on earlier work by Tobias Jakobi.
    >
    > Please remove it from each patch description.
    >
    >>
    >> 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 | 51 +++++++++++++++++++++++++++++++++++++++--------
    >> include/linux/devfreq.h | 7 +++++++
    >> 2 files changed, 50 insertions(+), 8 deletions(-)
    >>
    >> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
    >> index a9fd61b..36bed24 100644
    >> --- a/drivers/devfreq/devfreq.c
    >> +++ b/drivers/devfreq/devfreq.c
    >> @@ -316,6 +316,10 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
    >> "Couldn't update frequency transition information.\n");
    >>
    >> devfreq->previous_freq = new_freq;
    >> +
    >> + if (devfreq->suspend_freq)
    >> + devfreq->resume_freq = cur_freq;
    >> +
    >> return err;
    >> }
    >>
    >> @@ -667,6 +671,9 @@ struct devfreq *devfreq_add_device(struct device *dev,
    >> }
    >> devfreq->max_freq = devfreq->scaling_max_freq;
    >>
    >> + devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
    >> + atomic_set(&devfreq->suspend_count, 0);
    >> +
    >> dev_set_name(&devfreq->dev, "devfreq%d",
    >> atomic_inc_return(&devfreq_no));
    >> err = device_register(&devfreq->dev);
    >> @@ -867,14 +874,28 @@ EXPORT_SYMBOL(devm_devfreq_remove_device);
    >> */
    >> int devfreq_suspend_device(struct devfreq *devfreq)
    >> {
    >> + int ret;
    >> +
    >> if (!devfreq)
    >> return -EINVAL;
    >>
    >> - if (!devfreq->governor)
    >> - return 0;
    >> + if (devfreq->governor) {
    >> + ret = devfreq->governor->event_handler(devfreq,
    >> + DEVFREQ_GOV_SUSPEND, NULL);
    >> + if (ret)
    >> + return ret;
    >> + }
    >> +
    >> + if (devfreq->suspend_freq) {
    >> + if (atomic_inc_return(&devfreq->suspend_count) > 1)
    >> + return 0;
    >> +
    >> + ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
    >> + if (ret)
    >> + return ret;
    >> + }
    >>
    >> - return devfreq->governor->event_handler(devfreq,
    >> - DEVFREQ_GOV_SUSPEND, NULL);
    >> + return 0;
    >> }
    >> EXPORT_SYMBOL(devfreq_suspend_device);
    >>
    >> @@ -888,14 +909,28 @@ EXPORT_SYMBOL(devfreq_suspend_device);
    >> */
    >> int devfreq_resume_device(struct devfreq *devfreq)
    >> {
    >> + int ret;
    >> +
    >> if (!devfreq)
    >> return -EINVAL;
    >>
    >> - if (!devfreq->governor)
    >> - return 0;
    >> + if (devfreq->resume_freq) {
    >> + if (atomic_dec_return(&devfreq->suspend_count) >= 1)
    >> + return 0;
    >>
    >> - return devfreq->governor->event_handler(devfreq,
    >> - DEVFREQ_GOV_RESUME, NULL);
    >> + ret = devfreq_set_target(devfreq, devfreq->resume_freq, 0);
    >> + if (ret)
    >> + return ret;
    >> + }
    >> +
    >> + if (devfreq->governor) {
    >> + ret = devfreq->governor->event_handler(devfreq,
    >> + DEVFREQ_GOV_RESUME, NULL);
    >> + if (ret)
    >> + return ret;
    >> + }
    >> +
    >> + return 0;
    >> }
    >> EXPORT_SYMBOL(devfreq_resume_device);
    >>
    >> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
    >> index e4963b0..d985199 100644
    >> --- a/include/linux/devfreq.h
    >> +++ b/include/linux/devfreq.h
    >> @@ -131,6 +131,9 @@ struct devfreq_dev_profile {
    >> * @scaling_min_freq: Limit minimum frequency requested by OPP interface
    >> * @scaling_max_freq: Limit maximum frequency requested by OPP interface
    >> * @stop_polling: devfreq polling status of a device.
    >> + * @suspend_freq: frequency of a device set during suspend phase.
    >> + * @resume_freq: frequency of a device set in resume phase.
    >> + * @suspend_count: suspend requests counter for a device.
    >> * @total_trans: Number of devfreq transitions
    >> * @trans_table: Statistics of devfreq transitions
    >> * @time_in_state: Statistics of devfreq states
    >> @@ -167,6 +170,10 @@ struct devfreq {
    >> unsigned long scaling_max_freq;
    >> bool stop_polling;
    >>
    >> + unsigned long suspend_freq;
    >> + unsigned long resume_freq;
    >> + atomic_t suspend_count;
    >> +
    >> /* information for device frequency transition */
    >> unsigned int total_trans;
    >> unsigned int *trans_table;
    >>
    >
    >


    --
    Best Regards,
    Chanwoo Choi
    Samsung Electronics

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