From: Fabrice Gasnier fabrice.gasnier@st.com
[ Upstream commit c537d3457542a398caa1fe58e0976c5f83cf7281 ]
When the ADC is runtime suspended and starting a conversion, the stm32-adc driver calls pm_runtime_get_sync() that gets cascaded to the parent (e.g. runtime resume of stm32-adc-core driver). This also kicks the autosuspend delay (e.g. 2s) of the parent. Once the ADC is active, calling pm_runtime_get_sync() again (upon a new capture) won't kick the autosuspend delay for the parent (stm32-adc-core driver) as already active.
Currently, this makes the stm32-adc-core driver go in suspend state every 2s when doing slow polling. As an example, doing a capture, e.g. cat in_voltageY_raw at a 0.2s rate, the auto suspend delay for the parent isn't refreshed. Once it expires, the parent immediately falls into runtime suspended state, in between two captures, as soon as the child driver falls into runtime suspend state: - e.g. after 2s, + child calls pm_runtime_put_autosuspend() + 100ms autosuspend delay of the child. - stm32-adc-core switches off regulators, clocks and so on. - They get switched on back again 100ms later in this example (at 2.2s).
So, use runtime_idle() callback in stm32-adc-core driver to call pm_runtime_mark_last_busy() for the parent driver (stm32-adc-core), to avoid this.
Fixes: 9bdbb1139ca1 ("iio: adc: stm32-adc: add power management support") Signed-off-by: Fabrice Gasnier fabrice.gasnier@st.com Reviewed-by: Ulf Hansson ulf.hansson@linaro.org Link: https://lore.kernel.org/r/1593615328-5180-1-git-send-email-fabrice.gasnier@s... Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iio/adc/stm32-adc-core.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/adc/stm32-adc-core.c b/drivers/iio/adc/stm32-adc-core.c index 0e2068ec068b8..358636954619d 100644 --- a/drivers/iio/adc/stm32-adc-core.c +++ b/drivers/iio/adc/stm32-adc-core.c @@ -794,6 +794,13 @@ static int stm32_adc_core_runtime_resume(struct device *dev) { return stm32_adc_core_hw_start(dev); } + +static int stm32_adc_core_runtime_idle(struct device *dev) +{ + pm_runtime_mark_last_busy(dev); + + return 0; +} #endif
static const struct dev_pm_ops stm32_adc_core_pm_ops = { @@ -801,7 +808,7 @@ static const struct dev_pm_ops stm32_adc_core_pm_ops = { pm_runtime_force_resume) SET_RUNTIME_PM_OPS(stm32_adc_core_runtime_suspend, stm32_adc_core_runtime_resume, - NULL) + stm32_adc_core_runtime_idle) };
static const struct stm32_adc_priv_cfg stm32f4_adc_priv_cfg = {