FROMLIST: PM / devfreq: Fix handling of min/max_freq == 0
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>
(am from https://patchwork.kernel.org/patch/10465203/)
BUG=b:74321682, b:73050145
TEST=build and boot on dru
Change-Id: Ic0f2ebc3a2bfe682a02b62275fe59652f0cd49f9
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1102134
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
1 file changed
