On 3/10/21 12:00 PM, Dong Aisheng wrote:

On Wed, Mar 10, 2021 at 12:20 AM Chanwoo Choi [off-list ref] wrote:

quoted

On 21. 3. 9. 오후 9:58, Dong Aisheng wrote:

quoted

Check .get_dev_status() in devfreq_update_stats in case it's abused
when a device does not provide it.

Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
---
  drivers/devfreq/governor.h | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
index 31af6d072a10..67a6dbdd5d23 100644
--- a/drivers/devfreq/governor.h
+++ b/drivers/devfreq/governor.h

@@ -89,6 +89,9 @@ int devfreq_update_target(struct devfreq *devfreq, unsigned long freq);

  static inline int devfreq_update_stats(struct devfreq *df)
  {
+     if (!df->profile->get_dev_status)
+             return -EINVAL;
+

I'm considering the following method instead of returning the error
when .get_dev_status is NULL.

        if (!df->profile->get_dev_status) {
                df->last_status.total_time = 0;
                df->last_status.busy_time = 0;
                df->last_status.current_frequency = 0;
                return 0;
        }

I might  suggest not cause it's meaningless for ondemand governor but
introducing confusing. Simply return error could make the life a bit easier.
does it make sense to you?

Actually, I considered the some corner case as following:
We can see the simple_ondemand governor through available_governors
even if the devfreq driver doesn't implement the .get_dev_status.
In this corner case, My intention tried to prevent the error
on this case. But, actually, it is different issue. I'll fix
this issue when get_dev_status is NULL, don't show the
simple_ondemand governor name through available_governors
on other patch.

And I applied it. Thanks.

Regards
Aisheng

quoted

quoted

      return df->profile->get_dev_status(df->dev.parent, &df->last_status);
  }
  #endif /* _GOVERNOR_H */

--
Best Regards,
Samsung Electronics
Chanwoo Choi

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics