From: Matthias Kaehlcke <mka@chromium.org>
To: MyungJoo Ham <myungjoo.ham@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>,
Chanwoo Choi <cw00.choi@samsung.com>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
Brian Norris <briannorris@chromium.org>,
Douglas Anderson <dianders@chromium.org>,
Enric Balletbo i Serra <enric.balletbo@collabora.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Viresh Kumar <viresh.kumar@linaro.org>,
Lee Jones <lee.jones@linaro.org>,
Matthias Kaehlcke <mka@chromium.org>
Subject: [PATCH v3 02/12] PM / devfreq: Fix handling of min/max_freq == 0
Date: Thu, 14 Jun 2018 12:47:02 -0700 [thread overview]
Message-ID: <20180614194712.102134-3-mka@chromium.org> (raw)
In-Reply-To: <20180614194712.102134-1-mka@chromium.org>
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>
---
Changes in v3:
- none
Changes in v2:
- handle freq tables sorted in ascending and descending order in
min/max_freq_store()
- use same order for conditional statements in min/max_freq_store()
drivers/devfreq/devfreq.c | 42 ++++++++++++++++++++++++++++-----------
1 file changed, 30 insertions(+), 12 deletions(-)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 0057ef5b0a98..6f604f8b2b81 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -283,11 +283,11 @@ 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 */
}
@@ -1122,18 +1122,27 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
{
struct devfreq *df = to_devfreq(dev);
unsigned long value;
+ unsigned long *freq_table;
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 {
+ freq_table = df->profile->freq_table;
+ /* typical order is ascending, some drivers use descending */
+ 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;
@@ -1157,18 +1166,27 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
{
struct devfreq *df = to_devfreq(dev);
unsigned long value;
+ unsigned long *freq_table;
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 {
+ freq_table = df->profile->freq_table;
+ /* typical order is ascending, some drivers use descending */
+ 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;
--
2.18.0.rc1.242.g61856ae69a-goog
next prev parent reply other threads:[~2018-06-14 19:50 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-14 19:47 [PATCH v3 00/12] Add throttler driver for non-thermal throttling Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 01/12] PM / devfreq: Init user limits from OPP limits, not viceversa Matthias Kaehlcke
2018-06-15 21:06 ` Brian Norris
2018-06-15 21:25 ` Matthias Kaehlcke
2018-06-14 19:47 ` Matthias Kaehlcke [this message]
2018-06-18 20:12 ` [PATCH v3 02/12] PM / devfreq: Fix handling of min/max_freq == 0 Brian Norris
2018-06-14 19:47 ` [PATCH v3 03/12] PM / devfreq: Don't adjust to user limits in governors Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 04/12] PM / devfreq: Add struct devfreq_policy Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 05/12] PM / devfreg: Add support for policy notifiers Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 06/12] PM / devfreq: Make update_devfreq() public Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 07/12] PM / devfreq: export devfreq_class Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 08/12] cpufreq: Add stub for cpufreq_update_policy() Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 09/12] dt-bindings: PM / OPP: add opp-throttlers property Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 10/12] misc: throttler: Add core support for non-thermal throttling Matthias Kaehlcke
2018-06-18 23:03 ` Brian Norris
2018-06-18 23:59 ` Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 11/12] misc: throttler: Add Chrome OS EC throttler Matthias Kaehlcke
2018-06-18 23:34 ` Brian Norris
2018-06-14 19:47 ` [PATCH v3 12/12] mfd: cros_ec: Add throttler sub-device Matthias Kaehlcke
2018-06-18 23:21 ` Brian Norris
2018-06-19 8:41 ` Enric Balletbo Serra
2018-06-19 17:55 ` Matthias Kaehlcke
2018-06-19 17:43 ` Matthias Kaehlcke
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