linux-kernel - Re: [PATCH v4 02/24] PM / devfreq: tegra30: Keep interrupt disabled while governor is stopped

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Message-ID: <6c517d04-cf99-f907-e74d-9fba99405a53@gmail.com>
Date:   Tue, 16 Jul 2019 16:03:46 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Chanwoo Choi <cw00.choi@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:     linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 02/24] PM / devfreq: tegra30: Keep interrupt disabled
 while governor is stopped

16.07.2019 14:47, Chanwoo Choi пишет:
> On 19. 7. 8. 오전 7:32, Dmitry Osipenko wrote:
>> There is no real need to keep interrupt always-enabled, will be nicer
>> to keep it disabled while governor is inactive.
>>
>> Suggested-by: Thierry Reding <thierry.reding@...il.com>
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>  drivers/devfreq/tegra30-devfreq.c | 43 ++++++++++++++++---------------
>>  1 file changed, 22 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
>> index a27300f40b0b..5e2b133babdd 100644
>> --- a/drivers/devfreq/tegra30-devfreq.c
>> +++ b/drivers/devfreq/tegra30-devfreq.c
>> @@ -11,6 +11,7 @@
>>  #include <linux/devfreq.h>
>>  #include <linux/interrupt.h>
>>  #include <linux/io.h>
>> +#include <linux/irq.h>
>>  #include <linux/module.h>
>>  #include <linux/mod_devicetable.h>
>>  #include <linux/platform_device.h>
>> @@ -416,8 +417,6 @@ static void tegra_actmon_start(struct tegra_devfreq *tegra)
>>  {
>>  	unsigned int i;
>>  
>> -	disable_irq(tegra->irq);
>> -
>>  	actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
>>  		      ACTMON_GLB_PERIOD_CTRL);
>>  
>> @@ -442,8 +441,6 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
>>  	}
>>  
>>  	actmon_write_barrier(tegra);
>> -
>> -	enable_irq(tegra->irq);
>>  }
>>  
>>  static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
>> @@ -552,6 +549,12 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
>>  {
>>  	struct tegra_devfreq *tegra = dev_get_drvdata(devfreq->dev.parent);
>>  
>> +	/*
>> +	 * Couple device with the governor early as it is needed at
>> +	 * the moment of governor's start (used by ISR).
>> +	 */
>> +	tegra->devfreq = devfreq;
> 
> I'm not sure it is necessary. Almost devfreq device get
> the devfreq instance on probe timing through devfreq_add_device directly.

This is necessary because this assignment is for the "governor" and not
the "device". Governor is started during of devfreq_add_device(), hence
there is no better way to assign device to the driver's governor.

>> +
>>  	switch (event) {
>>  	case DEVFREQ_GOV_START:
>>  		devfreq_monitor_start(devfreq);
>> @@ -586,10 +589,11 @@ static struct devfreq_governor tegra_devfreq_governor = {
>>  
>>  static int tegra_devfreq_probe(struct platform_device *pdev)
>>  {
>> -	struct tegra_devfreq *tegra;
>>  	struct tegra_devfreq_device *dev;
>> -	unsigned int i;
>> +	struct tegra_devfreq *tegra;
>> +	struct devfreq *devfreq;
>>  	unsigned long rate;
>> +	unsigned int i;
>>  	int err;
>>  
>>  	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
>> @@ -625,6 +629,16 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>>  	}
>>  	tegra->irq = err;
>>  
>> +	irq_set_status_flags(tegra->irq, IRQ_NOAUTOEN);
>> +
>> +	err = devm_request_threaded_irq(&pdev->dev, tegra->irq, NULL,
>> +					actmon_thread_isr, IRQF_ONESHOT,
>> +					"tegra-devfreq", tegra);
>> +	if (err) {
>> +		dev_err(&pdev->dev, "Interrupt request failed: %d\n", err);
>> +		return err;
>> +	}
>> +
>>  	reset_control_assert(tegra->reset);
>>  
>>  	err = clk_prepare_enable(tegra->clock);
>> @@ -672,28 +686,15 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>>  	}
>>  
>>  	tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
>> -	tegra->devfreq = devfreq_add_device(&pdev->dev,
>> -					    &tegra_devfreq_profile,
>> -					    "tegra_actmon",
>> -					    NULL);
>> +	devfreq = devfreq_add_device(&pdev->dev, &tegra_devfreq_profile,
>> +				     "tegra_actmon", NULL);
>>  	if (IS_ERR(tegra->devfreq)) {
> 
> Have to check 'devfreq' instead of 'tegra->devfreq'.
> Did you test it? It might be failed because 'tegra->devfreq is NULL.

That's a good catch! Thank you very much.

>>  		err = PTR_ERR(tegra->devfreq);
> 
> ditto.

Ok