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PM / devfreq: Fix handling of min/max_freq == 0

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Commit ab8f58ad72 ("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 f1d981eaec ("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: f1d981eaec ("PM / devfreq: Use the available min/max frequency")
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
This commit is contained in:
Matthias Kaehlcke 2018-08-03 13:05:09 -07:00 committed by MyungJoo Ham
parent d0e464205b
commit df5cf4a361
1 changed files with 30 additions and 12 deletions
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42
drivers/devfreq/devfreq.c
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@ -324,11 +324,11 @@ int update_devfreq(struct devfreq *devfreq)
max_freq = min(devfreq->scaling_max_freq, devfreq->max_freq);
min_freq = max(devfreq->scaling_min_freq, devfreq->min_freq);
if (min_freq && freq < min_freq) {
if (freq < min_freq) {
freq = min_freq;
flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
}
if (max_freq && freq > max_freq) {
if (freq > max_freq) {
freq = max_freq;
flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
}
@ -1168,17 +1168,26 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
struct devfreq *df = to_devfreq(dev);
unsigned long value;
int ret;
unsigned long max;
ret = sscanf(buf, "%lu", &value);
if (ret != 1)
return -EINVAL;
mutex_lock(&df->lock);
max = df->max_freq;
if (value && max && value > max) {
ret = -EINVAL;
goto unlock;
if (value) {
if (value > df->max_freq) {
ret = -EINVAL;
goto unlock;
}
} else {
unsigned long *freq_table = df->profile->freq_table;
/* Get minimum frequency according to sorting order */
if (freq_table[0] < freq_table[df->profile->max_state - 1])
value = freq_table[0];
else
value = freq_table[df->profile->max_state - 1];
}
df->min_freq = value;
@ -1203,17 +1212,26 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
struct devfreq *df = to_devfreq(dev);
unsigned long value;
int ret;
unsigned long min;
ret = sscanf(buf, "%lu", &value);
if (ret != 1)
return -EINVAL;
mutex_lock(&df->lock);
min = df->min_freq;
if (value && min && value < min) {
ret = -EINVAL;
goto unlock;
if (value) {
if (value < df->min_freq) {
ret = -EINVAL;
goto unlock;
}
} else {
unsigned long *freq_table = df->profile->freq_table;
/* Get maximum frequency according to sorting order */
if (freq_table[0] < freq_table[df->profile->max_state - 1])
value = freq_table[df->profile->max_state - 1];
else
value = freq_table[0];
}
df->max_freq = value;