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SubjectRe: [PATCH v2] thermal: devfreq_cooling: Use PM QoS to set frequency limits
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Hi Matthias,

I just saw this email below the patch. I wasn't aware that you
are working on this. I will have to update my changes...

It looks good to me.
Unfortunately, it does not apply on top of Amit's commit
1b5cb9570670a6277cc0 thermal: devfreq_cooling: Appease the kernel-doc deity

Could you check this?

Other then that

Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

Regards,
Lukasz

On 3/12/20 12:35 AM, Matthias Kaehlcke wrote:
> Is any further action needed from my side or can this land?
>
> Thanks
>
> Matthias
>
> On Fri, Jan 17, 2020 at 02:22:02PM +0900, Chanwoo Choi wrote:
>> On 1/17/20 8:12 AM, Matthias Kaehlcke wrote:
>>> Now that devfreq supports limiting the frequency range of a device
>>> through PM QoS make use of it instead of disabling OPPs that should
>>> not be used.
>>>
>>> The switch from disabling OPPs to PM QoS introduces a subtle behavioral
>>> change in case of conflicting requests (min > max): PM QoS gives
>>> precedence to the MIN_FREQUENCY request, while higher OPPs disabled
>>> with dev_pm_opp_disable() would override MIN_FREQUENCY.
>>>
>>> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
>>> ---
>>>
>>> Changes in v2:
>>> - added documentation for 'req_max_freq'
>>> - fixed jumps in of_devfreq_cooling_register_power() unwind
>>> - added comment about behavioral change to the commit message
>>>
>>> drivers/thermal/devfreq_cooling.c | 70 ++++++++++---------------------
>>> 1 file changed, 23 insertions(+), 47 deletions(-)
>>>
>>> diff --git a/drivers/thermal/devfreq_cooling.c b/drivers/thermal/devfreq_cooling.c
>>> index ef59256887ff63..cbbaf5bc425d1a 100644
>>> --- a/drivers/thermal/devfreq_cooling.c
>>> +++ b/drivers/thermal/devfreq_cooling.c
>>> @@ -24,11 +24,13 @@
>>> #include <linux/idr.h>
>>> #include <linux/slab.h>
>>> #include <linux/pm_opp.h>
>>> +#include <linux/pm_qos.h>
>>> #include <linux/thermal.h>
>>>
>>> #include <trace/events/thermal.h>
>>>
>>> -#define SCALE_ERROR_MITIGATION 100
>>> +#define HZ_PER_KHZ 1000
>>> +#define SCALE_ERROR_MITIGATION 100
>>>
>>> static DEFINE_IDA(devfreq_ida);
>>>
>>> @@ -53,6 +55,8 @@ static DEFINE_IDA(devfreq_ida);
>>> * 'utilization' (which is 'busy_time / 'total_time').
>>> * The 'res_util' range is from 100 to (power_table[state] * 100)
>>> * for the corresponding 'state'.
>>> + * @req_max_freq: PM QoS request for limiting the maximum frequency
>>> + * of the devfreq device.
>>> */
>>> struct devfreq_cooling_device {
>>> int id;
>>> @@ -65,49 +69,9 @@ struct devfreq_cooling_device {
>>> struct devfreq_cooling_power *power_ops;
>>> u32 res_util;
>>> int capped_state;
>>> + struct dev_pm_qos_request req_max_freq;
>>> };
>>>
>>> -/**
>>> - * partition_enable_opps() - disable all opps above a given state
>>> - * @dfc: Pointer to devfreq we are operating on
>>> - * @cdev_state: cooling device state we're setting
>>> - *
>>> - * Go through the OPPs of the device, enabling all OPPs until
>>> - * @cdev_state and disabling those frequencies above it.
>>> - */
>>> -static int partition_enable_opps(struct devfreq_cooling_device *dfc,
>>> - unsigned long cdev_state)
>>> -{
>>> - int i;
>>> - struct device *dev = dfc->devfreq->dev.parent;
>>> -
>>> - for (i = 0; i < dfc->freq_table_size; i++) {
>>> - struct dev_pm_opp *opp;
>>> - int ret = 0;
>>> - unsigned int freq = dfc->freq_table[i];
>>> - bool want_enable = i >= cdev_state ? true : false;
>>> -
>>> - opp = dev_pm_opp_find_freq_exact(dev, freq, !want_enable);
>>> -
>>> - if (PTR_ERR(opp) == -ERANGE)
>>> - continue;
>>> - else if (IS_ERR(opp))
>>> - return PTR_ERR(opp);
>>> -
>>> - dev_pm_opp_put(opp);
>>> -
>>> - if (want_enable)
>>> - ret = dev_pm_opp_enable(dev, freq);
>>> - else
>>> - ret = dev_pm_opp_disable(dev, freq);
>>> -
>>> - if (ret)
>>> - return ret;
>>> - }
>>> -
>>> - return 0;
>>> -}
>>> -
>>> static int devfreq_cooling_get_max_state(struct thermal_cooling_device *cdev,
>>> unsigned long *state)
>>> {
>>> @@ -134,7 +98,7 @@ static int devfreq_cooling_set_cur_state(struct thermal_cooling_device *cdev,
>>> struct devfreq_cooling_device *dfc = cdev->devdata;
>>> struct devfreq *df = dfc->devfreq;
>>> struct device *dev = df->dev.parent;
>>> - int ret;
>>> + unsigned long freq;
>>>
>>> if (state == dfc->cooling_state)
>>> return 0;
>>> @@ -144,9 +108,10 @@ static int devfreq_cooling_set_cur_state(struct thermal_cooling_device *cdev,
>>> if (state >= dfc->freq_table_size)
>>> return -EINVAL;
>>>
>>> - ret = partition_enable_opps(dfc, state);
>>> - if (ret)
>>> - return ret;
>>> + freq = dfc->freq_table[state];
>>> +
>>> + dev_pm_qos_update_request(&dfc->req_max_freq,
>>> + DIV_ROUND_UP(freq, HZ_PER_KHZ));
>>>
>>> dfc->cooling_state = state;
>>>
>>> @@ -529,9 +494,15 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
>>> if (err)
>>> goto free_dfc;
>>>
>>> - err = ida_simple_get(&devfreq_ida, 0, 0, GFP_KERNEL);
>>> + err = dev_pm_qos_add_request(df->dev.parent, &dfc->req_max_freq,
>>> + DEV_PM_QOS_MAX_FREQUENCY,
>>> + PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
>>> if (err < 0)
>>> goto free_tables;
>>> +
>>> + err = ida_simple_get(&devfreq_ida, 0, 0, GFP_KERNEL);
>>> + if (err < 0)
>>> + goto remove_qos_req;
>>> dfc->id = err;
>>>
>>> snprintf(dev_name, sizeof(dev_name), "thermal-devfreq-%d", dfc->id);
>>> @@ -552,6 +523,10 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
>>>
>>> release_ida:
>>> ida_simple_remove(&devfreq_ida, dfc->id);
>>> +
>>> +remove_qos_req:
>>> + dev_pm_qos_remove_request(&dfc->req_max_freq);
>>> +
>>> free_tables:
>>> kfree(dfc->power_table);
>>> kfree(dfc->freq_table);
>>> @@ -600,6 +575,7 @@ void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
>>>
>>> thermal_cooling_device_unregister(dfc->cdev);
>>> ida_simple_remove(&devfreq_ida, dfc->id);
>>> + dev_pm_qos_remove_request(&dfc->req_max_freq);
>>> kfree(dfc->power_table);
>>> kfree(dfc->freq_table);
>>>
>>>
>>
>> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>>
>> --
>> Best Regards,
>> Chanwoo Choi
>> Samsung Electronics

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