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

Dmitry Osipenko
2019-07-16T13:03:55Z

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@gmail.com>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.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