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

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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