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SubjectRe: [PATCH 2/4] pwm: stm32-lp: Add power management support
On Tue, Feb 05, 2019 at 01:40:27PM +0100, Fabrice Gasnier wrote:
> Add suspend/resume PM sleep ops. When going to low power, disable
> active PWM channel. Active PWM channel is resumed, by calling
> pwm_apply_state(). This is inspired by Thierry's comment in [1].
> Don't touch inactive channels, as it may be used by other LPTimer MFD
> child driver.
> [1]https://lkml.org/lkml/2017/12/5/175
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> ---
> drivers/pwm/pwm-stm32-lp.c | 38 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/drivers/pwm/pwm-stm32-lp.c b/drivers/pwm/pwm-stm32-lp.c
> index 0059b24c..0c40d48 100644
> --- a/drivers/pwm/pwm-stm32-lp.c
> +++ b/drivers/pwm/pwm-stm32-lp.c
> @@ -13,6 +13,7 @@
> #include <linux/mfd/stm32-lptimer.h>
> #include <linux/module.h>
> #include <linux/of.h>
> +#include <linux/pinctrl/consumer.h>
> #include <linux/platform_device.h>
> #include <linux/pwm.h>
>
> @@ -20,6 +21,8 @@ struct stm32_pwm_lp {
> struct pwm_chip chip;
> struct clk *clk;
> struct regmap *regmap;
> + struct pwm_state suspend;
> + bool suspended;
> };
>
> static inline struct stm32_pwm_lp *to_stm32_pwm_lp(struct pwm_chip *chip)
> @@ -223,6 +226,40 @@ static int stm32_pwm_lp_remove(struct platform_device *pdev)
> return pwmchip_remove(&priv->chip);
> }
>
> +#ifdef CONFIG_PM_SLEEP

You might consider dropping ifdefs and marking pm functions with
__maybe_unused instead. In case CONFIG_PM_SLEEP=n then these two guys
will be removed and pm ops structure will be empty.

> +static int stm32_pwm_lp_suspend(struct device *dev)
> +{
> + struct stm32_pwm_lp *priv = dev_get_drvdata(dev);
> +

I guess you first need to get platform_device from dev and eventually
stm32_pwm_lp. Wondering how this works now.

> + pwm_get_state(&priv->chip.pwms[0], &priv->suspend);
> + priv->suspended = priv->suspend.enabled;
> +
> + /* safe to call pwm_disable() for already disabled pwm */
> + pwm_disable(&priv->chip.pwms[0]);
> +
> + return pinctrl_pm_select_sleep_state(dev);
> +}
> +
> +static int stm32_pwm_lp_resume(struct device *dev)
> +{
> + struct stm32_pwm_lp *priv = dev_get_drvdata(dev);
> + int ret;
> +
> + ret = pinctrl_pm_select_default_state(dev);
> + if (ret)
> + return ret;
> +
> + /* Only restore suspended pwm, not to disrupt other MFD child */
> + if (!priv->suspended)
> + return 0;

Would it make sense to use suspend.enabled directly?

> +
> + return pwm_apply_state(&priv->chip.pwms[0], &priv->suspend);
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(stm32_pwm_lp_pm_ops, stm32_pwm_lp_suspend,
> + stm32_pwm_lp_resume);
> +
> static const struct of_device_id stm32_pwm_lp_of_match[] = {
> { .compatible = "st,stm32-pwm-lp", },
> {},
> @@ -235,6 +272,7 @@ static int stm32_pwm_lp_remove(struct platform_device *pdev)
> .driver = {
> .name = "stm32-pwm-lp",
> .of_match_table = of_match_ptr(stm32_pwm_lp_of_match),
> + .pm = &stm32_pwm_lp_pm_ops,
> },
> };
> module_platform_driver(stm32_pwm_lp_driver);
> --
> 1.9.1
>

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