On Tuesday, November 26, 2019 4:17:09 PM CET Leonard Crestez wrote: > Support for frequency limits in dev_pm_qos was removed when cpufreq was > switched to freq_qos, this series attempts to restore it by > reimplementing on top of freq_qos. > > Discussion about removal is here: > https://lore.kernel.org/linux-pm/VI1PR04MB7023DF47D046AEADB4E051EBEE680@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/T/#u > > The cpufreq core switched away because it needs contraints at the level > of a "cpufreq_policy" which cover multiple cpus so dev_pm_qos coupling > to struct device was not useful. Cpufreq could only use dev_pm_qos by > implementing an additional layer of aggregation anyway. > > However in the devfreq subsystem scaling is always performed on a per-device > basis so dev_pm_qos is a very good match. Support for dev_pm_qos in devfreq > core is here (latest version, no dependencies outside this series): > > https://patchwork.kernel.org/cover/11252409/ > > That series is RFC mostly because it needs these PM core patches. > Earlier versions got entangled in some locking cleanups but those are > not strictly necessary to get dev_pm_qos functionality. > > In theory if freq_qos is extended to handle conflicting min/max values then > this sharing would be valuable. Right now freq_qos just ties two unrelated > pm_qos aggregations for min and max freq. > > --- > This is implemented by embeding a freq_qos_request inside dev_pm_qos_request: > the data field was already an union in order to deal with flag requests. > > The internal freq_qos_apply is exported so that it can be called from > dev_pm_qos apply_constraints. > > The dev_pm_qos_constraints_destroy function has no obvious equivalent in > freq_qos and the whole approach of "removing requests" is somewhat dubios: > request objects should be owned by consumers and the list of qos requests > will most likely be empty when the target device is deleted. Series follows > current pattern for dev_pm_qos. > > First two patches can be applied separately. > > Changes since v3: > * Fix s/QOS/QoS in patch 2 title > * Improves comments in kunit test > * Fix assertions after freq_qos_remove_request > * Remove (c) from NXP copyright header > * Wrap long lines in qos.c to be under 80 chars. This fixes checkpatch but the > rule is already broken by code in the files. > * Collect reviews > Link to v3: https://patchwork.kernel.org/cover/11260627/ > > Changes since v2: > * #define PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE FREQ_QOS_MAX_DEFAULT_VALUE > * #define FREQ_QOS_MAX_DEFAULT_VALUE S32_MAX (in new patch) > * Add initial kunit test for freq_qos, validating the MAX_DEFAULT_VALUE found > by Matthias and another recent fix. Testing this should be easier! > Link to v2: https://patchwork.kernel.org/cover/11250413/ > > Changes since v1: > * Don't rename or EXPORT_SYMBOL_GPL the freq_qos_apply function; just > drop the static marker. > Link to v1: https://patchwork.kernel.org/cover/11212887/ > > Leonard Crestez (4): > PM / QoS: Initial kunit test > PM / QoS: Redefine FREQ_QOS_MAX_DEFAULT_VALUE to S32_MAX > PM / QoS: Reorder pm_qos/freq_qos/dev_pm_qos structs > PM / QoS: Restore DEV_PM_QOS_MIN/MAX_FREQUENCY > > drivers/base/Kconfig | 4 ++ > drivers/base/power/Makefile | 1 + > drivers/base/power/qos-test.c | 117 ++++++++++++++++++++++++++++++++++ > drivers/base/power/qos.c | 73 +++++++++++++++++++-- > include/linux/pm_qos.h | 86 ++++++++++++++----------- > kernel/power/qos.c | 4 +- > 6 files changed, 242 insertions(+), 43 deletions(-) > create mode 100644 drivers/base/power/qos-test.c > > I have applied the whole series as 5.5 material, but I have reordered the fix (patch [2/4]) before the rest of it and marked it for -stable. Thanks!
