Hi, Jonathan, On 03.12.2024 22:00, Jonathan Cameron wrote: > On Tue, 3 Dec 2024 13:13:07 +0200 > Claudiu <claudiu.beznea@xxxxxxxxx> wrote: > >> From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx> >> >> Enable runtime PM autosuspend support for the rzg2l_adc driver. With this >> change, consecutive conversion requests will no longer cause the device to >> be runtime-enabled/disabled after each request. Instead, the device will >> transition based on the delay configured by the user. >> >> This approach reduces the frequency of hardware register access during >> runtime PM suspend/resume cycles, thereby saving CPU cycles. The default >> autosuspend delay is set to zero to maintain the previous driver behavior. > > Unless you have a weird user who is polling slow enough to not trigger > autosuspend with a non zero period, but is still saving power I'm not convinced > anyone will notice if you just enable this for a sensible autosuspend delay. > There will of course be a small increase in power usage for each read but > hopefully that is trivial. > > So I'd not go with a default of 0, though what value makes sense depends > on the likely usecase + how much power is saved by going to sleep. > > If you really want to keep 0 I don't mind that much, just seems odd! I agree with you. I chose it like this as I got internal request (on other drivers enabling autosuspend support) to keep the previous behavior in place. Thank you for your review, Claudiu > > Jonathan > >> >> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx> >> --- >> drivers/iio/adc/rzg2l_adc.c | 9 +++++++-- >> 1 file changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/iio/adc/rzg2l_adc.c b/drivers/iio/adc/rzg2l_adc.c >> index eed2944bd98d..fda8b42ded81 100644 >> --- a/drivers/iio/adc/rzg2l_adc.c >> +++ b/drivers/iio/adc/rzg2l_adc.c >> @@ -207,7 +207,8 @@ static int rzg2l_adc_conversion(struct iio_dev *indio_dev, struct rzg2l_adc *adc >> rzg2l_adc_start_stop(adc, false); >> >> rpm_put: >> - pm_runtime_put_sync(dev); >> + pm_runtime_mark_last_busy(dev); >> + pm_runtime_put_autosuspend(dev); >> return ret; >> } >> >> @@ -372,7 +373,8 @@ static int rzg2l_adc_hw_init(struct device *dev, struct rzg2l_adc *adc) >> rzg2l_adc_writel(adc, RZG2L_ADM(3), reg); >> >> exit_hw_init: >> - pm_runtime_put_sync(dev); >> + pm_runtime_mark_last_busy(dev); >> + pm_runtime_put_autosuspend(dev); >> return ret; >> } >> >> @@ -412,6 +414,9 @@ static int rzg2l_adc_probe(struct platform_device *pdev) >> return PTR_ERR(adc->presetn); >> } >> >> + /* Default 0 for power saving. Can be overridden via sysfs. */ >> + pm_runtime_set_autosuspend_delay(dev, 0); >> + pm_runtime_use_autosuspend(dev); >> ret = devm_pm_runtime_enable(dev); >> if (ret) >> return ret; >
