Re: [PATCH v3 2/5] devfreq: add support for suspend/resume of a devfreq device
From: Chanwoo Choi <cw00.choi@samsung.com>
Date: 2018-12-06 01:18:02
Also in:
linux-devicetree, linux-pm, linux-samsung-soc, lkml
Hi Lukasz, On 2018년 12월 05일 20:05, Lukasz Luba wrote:
The patch prepares devfreq device for handling suspend/resume functionality. The new fields will store needed information during this process. Devfreq framework handles opp-suspend DT entry and there is no need of modyfications in the drivers code. It uses atomic variables to make sure no race condition affects the process. Suggested-by: Tobias Jakobi <redacted> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com> Signed-off-by: Lukasz Luba <redacted> --- drivers/devfreq/devfreq.c | 47 +++++++++++++++++++++++++++++++++++++++++------ include/linux/devfreq.h | 7 +++++++ 2 files changed, 48 insertions(+), 6 deletions(-)
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
quoted hunk ↗ jump to hunk
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index a9fd61b..46517b6 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c@@ -316,6 +316,10 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq, "Couldn't update frequency transition information.\n"); devfreq->previous_freq = new_freq; + + if (devfreq->suspend_freq) + devfreq->resume_freq = cur_freq; + return err; }@@ -667,6 +671,9 @@ struct devfreq *devfreq_add_device(struct device *dev, } devfreq->max_freq = devfreq->scaling_max_freq; + devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev); + atomic_set(&devfreq->suspend_count, 0); + dev_set_name(&devfreq->dev, "devfreq%d", atomic_inc_return(&devfreq_no)); err = device_register(&devfreq->dev);@@ -867,14 +874,28 @@ EXPORT_SYMBOL(devm_devfreq_remove_device); */ int devfreq_suspend_device(struct devfreq *devfreq) { + int ret; + if (!devfreq) return -EINVAL; - if (!devfreq->governor) + if (atomic_inc_return(&devfreq->suspend_count) > 1) return 0; - return devfreq->governor->event_handler(devfreq, - DEVFREQ_GOV_SUSPEND, NULL); + if (devfreq->governor) { + ret = devfreq->governor->event_handler(devfreq, + DEVFREQ_GOV_SUSPEND, NULL); + if (ret) + return ret; + } + + if (devfreq->suspend_freq) { + ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0); + if (ret) + return ret; + } + + return 0; } EXPORT_SYMBOL(devfreq_suspend_device);@@ -888,14 +909,28 @@ EXPORT_SYMBOL(devfreq_suspend_device); */ int devfreq_resume_device(struct devfreq *devfreq) { + int ret; + if (!devfreq) return -EINVAL; - if (!devfreq->governor) + if (atomic_dec_return(&devfreq->suspend_count) >= 1) return 0; - return devfreq->governor->event_handler(devfreq, - DEVFREQ_GOV_RESUME, NULL); + if (devfreq->resume_freq) { + ret = devfreq_set_target(devfreq, devfreq->resume_freq, 0); + if (ret) + return ret; + } + + if (devfreq->governor) { + ret = devfreq->governor->event_handler(devfreq, + DEVFREQ_GOV_RESUME, NULL); + if (ret) + return ret; + } + + return 0; } EXPORT_SYMBOL(devfreq_resume_device);diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h index e4963b0..d985199 100644 --- a/include/linux/devfreq.h +++ b/include/linux/devfreq.h@@ -131,6 +131,9 @@ struct devfreq_dev_profile { * @scaling_min_freq: Limit minimum frequency requested by OPP interface * @scaling_max_freq: Limit maximum frequency requested by OPP interface * @stop_polling: devfreq polling status of a device. + * @suspend_freq: frequency of a device set during suspend phase. + * @resume_freq: frequency of a device set in resume phase. + * @suspend_count: suspend requests counter for a device. * @total_trans: Number of devfreq transitions * @trans_table: Statistics of devfreq transitions * @time_in_state: Statistics of devfreq states@@ -167,6 +170,10 @@ struct devfreq { unsigned long scaling_max_freq; bool stop_polling; + unsigned long suspend_freq; + unsigned long resume_freq; + atomic_t suspend_count; + /* information for device frequency transition */ unsigned int total_trans; unsigned int *trans_table;
-- Best Regards, Chanwoo Choi Samsung Electronics _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel