Hello, This series addresses some additional review comments that were made by Thierry Reding to [1], makes several important changes to the driver, reducing interrupts activity, and adds new features. In the end I'm proposing myself as a maintainer for the Tegra devfreq drivers. [1] https://lore.kernel.org/lkml/0fb50eb1-a173-1756-6889-2526a10ac707@xxxxxxxxx/T/ Changelog: v9: Addressed review comments that were made by Chanwoo Choi to v8 by: 1. Updating the "Add new interrupt_driven flag for governors" patch in accordance to the comments. 2. Factoring out the change of the dependency threshold units into a separate patch: PM / devfreq: tegra30: Use kHz units for dependency threshold In this patch I also corrected the new threshold value because it was miscalculated in v8 using MCALL coefficient instead of MCCPU. Patch "Support variable polling interval" now again handles properly governor's enable-state while polling interval is changed, it won't start polling if governor is stopped. The problem was introduced in v8 when switched away from using devfreq->stop_polling because using tegra->cur_freq is not enough and the whole "stop_polling" logic needs to be duplicated in the driver. v8: Addressed review comments that were made by Chanwoo Choi to v7 by: 1. Taking into account suggestions that were made for the "Add new interrupt_driven flag for governors". 2. Patch "Support variable polling interval" now doesn't use devfreq->stop_polling and uses tegra->cur_freq instead. There is now a comment for the 256ms max polling interval limitation as well. The patch "Increase sampling period to 16ms" is dropped from the series for now since we found out that it doesn't bring much benefit. The cur_freq value is now refreshed after clk-notifier registration in the "Move clk-notifier's registration to governor's start" patch, for consistency. This also becomes useful for the "Support variable polling interval" patch since it now uses the cur_freq for tracking of the governor's enable-state. The patch "Support variable polling interval" now has a proper scaling of the dependency threshold value, which I missed to backport into v7 after dropping some of the v6 patches. The do_percent() function now doesn't suffer from integer overflow bug when freq, boosting and polling interval values are too large. v7: Addressed review comments that were made by Chanwoo Choi to v6 by: 1. Dropping patch "Ensure that target freq won't overflow". 2. Making "Use kHz units uniformly in the code" patch more easier for review and improving its commit's message. 3. The "Support variable polling interval" patch is reworked, now it doesn't touch things that should stay internal to devfreq core, like devfreq->stop_polling and etc. In a result a new generic interrupt_driven flag is available for devfreq governors (added in a new patch "Add new interrupt_driven flag for governors"). Patch "Set up watermarks properly" and related to it patches are dropped because I found a case where it doesn't work well. These patches need some more thought and not ready for now, I'll continue working on them. I extracted useful changes from the dropped patches and then tuned up MCCPU boost-down coefficient to keep ACTMON silent when system is idling, in a result there are these new patches: 1. Don't enable already enabled consecutive interrupts 2. Disable consecutive interrupts when appropriate 3. Tune up MCCPU boost-down coefficient v6: Addressed review comment that was made by Chanwoo Choi to v5 by squashing "Define ACTMON_DEV_CTRL_STOP" patch into the "Use CPUFreq notifier" patch. v5: Addressed review comments that were made by Chanwoo Choi to v4 by squashing few patches, dropping some questionable patches, rewording comments to the code, restructuring the code and etc. These patches are now dropped from the series: PM / devfreq: tegra30: Use tracepoints for debugging PM / devfreq: tegra30: Inline all one-line functions The interrupt-optimization patches are squashed into a single patch: PM / devfreq: tegra30: Reduce unnecessary interrupts activity because it's better to keep the optimizations as a separate change and this also helps to reduce code churning, since the code changes depend on a previous patch in order to stay cleaner. Fixed a lockup bug that I spotted recently, which is caused by a clk-notifier->cpufreq_get()->clk_set_rate() sequence. Now a non-blocking variant of CPU's frequency retrieving is used, i.e. cpufreq_quick_get(). Further optimized the CPUFreq notifier by postponing the delayed updating in accordance to the polling interval, this actually uncovered the above lockup bug. Implemented new minor driver feature in the new patch: PM / devfreq: tegra30: Support variable polling interval v4: Added two new patches to the series: PM / devfreq: tegra30: Synchronize average count on target's update PM / devfreq: tegra30: Increase sampling period to 16ms The first patch addresses problem where governor could get stuck due to outdated "average count" value which is snapshoted by ISR and there are cases where manual update of the value is required. The second patch is just a minor optimization. v3: Added support for tracepoints, replacing the debug messages. Fixed few more bugs with the help of tracepoints. New patches in this version: PM / devfreq: tegra30: Use tracepoints for debugging PM / devfreq: tegra30: Optimize CPUFreq notifier PM / devfreq: tegra30: Optimize upper consecutive watermark selection PM / devfreq: tegra30: Optimize upper average watermark selection PM / devfreq: tegra30: Include appropriate header Some of older patches of this series also got some extra minor polish. v2: Added more patches that are cleaning driver's code further and squashing another kHz conversion bug. The patch "Rework frequency management logic" of the v1 series is now converted to "Set up watermarks properly" because I found some problems in the original patch and then realized that there is no need to change the logic much. So the logic mostly preserved and only got improvements. The series is based on the today's linux-next (25 Jun) and takes into account minor changes that MyungJoo Ham made to the already queued patches from the first batch [1]. Dmitry Osipenko (19): PM / devfreq: tegra30: Change irq type to unsigned int PM / devfreq: tegra30: Keep interrupt disabled while governor is stopped PM / devfreq: tegra30: Handle possible round-rate error PM / devfreq: tegra30: Drop write-barrier PM / devfreq: tegra30: Fix integer overflow on CPU's freq max out PM / devfreq: tegra30: Use kHz units uniformly in the code PM / devfreq: tegra30: Use CPUFreq notifier PM / devfreq: tegra30: Move clk-notifier's registration to governor's start PM / devfreq: tegra30: Reset boosting on startup PM / devfreq: tegra30: Don't enable consecutive-down interrupt on startup PM / devfreq: tegra30: Constify structs PM / devfreq: tegra30: Include appropriate header PM / devfreq: tegra30: Don't enable already enabled consecutive interrupts PM / devfreq: tegra30: Disable consecutive interrupts when appropriate PM / devfreq: tegra30: Use kHz units for dependency threshold PM / devfreq: Add new interrupt_driven flag for governors PM / devfreq: tegra30: Support variable polling interval PM / devfreq: tegra30: Tune up MCCPU boost-down coefficient PM / devfreq: tegra20/30: Add Dmitry as a maintainer MAINTAINERS | 9 + drivers/devfreq/devfreq.c | 17 ++ drivers/devfreq/governor.h | 3 + drivers/devfreq/tegra30-devfreq.c | 417 ++++++++++++++++++++++-------- 4 files changed, 334 insertions(+), 112 deletions(-) -- 2.23.0
