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SubjectRE: [PATCH 02/11] PM / devfreq: Fix handling of min/max_freq == 0
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> Commit ab8f58ad72c4 ("PM / devfreq: Set min/max_freq when adding the
> devfreq device") initializes df->min/max_freq with the min/max OPP when
> the device is added. Later commit f1d981eaecf8 ("PM / devfreq: Use the
> available min/max frequency") adds df->scaling_min/max_freq and the
> following to the frequency adjustment code:
>
> max_freq = MIN(devfreq->scaling_max_freq, devfreq->max_freq);
>
> With the current handling of min/max_freq this is incorrect:
>
> Even though df->max_freq is now initialized to a value != 0 user space
> can still set it to 0, in this case max_freq would be 0 instead of
> df->scaling_max_freq as intended. In consequence the frequency adjustment
> is not performed:
>
> if (max_freq && freq > max_freq) {
> freq = max_freq;
>
> To fix this set df->min/max freq to the min/max OPP in max/max_freq_store,
> when the user passes a value of 0. This also prevents df->max_freq from
> being set below the min OPP when df->min_freq is 0, and similar for
> min_freq. Since it is now guaranteed that df->min/max_freq can't be 0 the
> checks for this case can be removed.
>
> Fixes: f1d981eaecf8 ("PM / devfreq: Use the available min/max frequency")
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> drivers/devfreq/devfreq.c | 30 ++++++++++++++++++------------
> 1 file changed, 18 insertions(+), 12 deletions(-)

Thanks a lot! Nice Catch.

Acked-by: MyungJoo Ham <myunngjoo.ham@samsung.com>

Cheers,
MyungJoo.

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