From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Clemens Gruber <clemens.gruber@pqgruber.com>
Cc: linux-pwm@vger.kernel.org,
Thierry Reding <thierry.reding@gmail.com>,
Sven Van Asbroeck <TheSven73@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 3/7] pwm: pca9685: Improve runtime PM behavior
Date: Mon, 29 Mar 2021 17:55:27 +0200 [thread overview]
Message-ID: <20210329155527.q3o25ubh33pmszsi@pengutronix.de> (raw)
In-Reply-To: <20210329125707.182732-3-clemens.gruber@pqgruber.com>
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On Mon, Mar 29, 2021 at 02:57:03PM +0200, Clemens Gruber wrote:
> The chip does not come out of POR in active state but in sleep state.
> To be sure (in case the bootloader woke it up) we force it to sleep in
> probe.
>
> On kernels without CONFIG_PM, we wake the chip in .probe and put it to
> sleep in .remove.
What is the effect of sleep state? Does it continue to oscilate it the
bootloader set up some configuration?
> Signed-off-by: Clemens Gruber <clemens.gruber@pqgruber.com>
> ---
> drivers/pwm/pwm-pca9685.c | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
> index fb026a25fb61..4d6684b90819 100644
> --- a/drivers/pwm/pwm-pca9685.c
> +++ b/drivers/pwm/pwm-pca9685.c
> @@ -469,14 +469,19 @@ static int pca9685_pwm_probe(struct i2c_client *client,
> return ret;
> }
>
> - /* The chip comes out of power-up in the active state */
> - pm_runtime_set_active(&client->dev);
> /*
> - * Enable will put the chip into suspend, which is what we
> - * want as all outputs are disabled at this point
> + * The chip comes out of power-up in the sleep state,
> + * but force it to sleep in case it was woken up before
> */
> + pca9685_set_sleep_mode(pca, true);
> + pm_runtime_set_suspended(&client->dev);
> pm_runtime_enable(&client->dev);
>
> + if (!IS_ENABLED(CONFIG_PM)) {
> + /* Wake the chip up on non-PM environments */
> + pca9685_set_sleep_mode(pca, false);
I admit I didn't grasp all the PM framework details, but I wonder if
it's right to first call set_sleep_mode(true) and then in some cases to
false again.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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next prev parent reply other threads:[~2021-03-29 15:56 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-29 12:57 [PATCH v6 1/7] pwm: pca9685: Switch to atomic API Clemens Gruber
2021-03-29 12:57 ` [PATCH v6 2/7] pwm: pca9685: Support hardware readout Clemens Gruber
2021-03-29 15:51 ` Uwe Kleine-König
2021-03-29 16:33 ` Clemens Gruber
2021-03-29 16:54 ` Uwe Kleine-König
2021-03-29 17:11 ` Clemens Gruber
2021-03-29 17:41 ` Uwe Kleine-König
2021-03-29 12:57 ` [PATCH v6 3/7] pwm: pca9685: Improve runtime PM behavior Clemens Gruber
2021-03-29 15:55 ` Uwe Kleine-König [this message]
2021-03-29 16:31 ` Clemens Gruber
2021-03-29 12:57 ` [PATCH v6 4/7] pwm: pca9685: Support staggered output ON times Clemens Gruber
2021-03-29 17:03 ` Uwe Kleine-König
2021-03-29 17:16 ` Clemens Gruber
2021-03-29 18:02 ` Uwe Kleine-König
2021-03-31 12:26 ` Clemens Gruber
2021-03-31 13:55 ` Clemens Gruber
2021-04-01 20:59 ` Uwe Kleine-König
2021-04-01 21:53 ` Clemens Gruber
2021-03-31 16:21 ` Thierry Reding
2021-04-01 7:50 ` Clemens Gruber
2021-04-01 13:47 ` Thierry Reding
2021-04-01 15:19 ` Clemens Gruber
2021-04-02 19:48 ` Uwe Kleine-König
2021-04-01 20:58 ` Uwe Kleine-König
2021-04-01 21:37 ` Clemens Gruber
2021-04-02 20:23 ` Uwe Kleine-König
2021-03-29 12:57 ` [PATCH v6 5/7] dt-bindings: pwm: pca9685: Add nxp,staggered-outputs property Clemens Gruber
2021-04-02 19:52 ` Uwe Kleine-König
2021-03-29 12:57 ` [PATCH v6 6/7] pwm: pca9685: Restrict period change for prescaler users Clemens Gruber
2021-03-29 17:15 ` Uwe Kleine-König
2021-03-29 17:33 ` Clemens Gruber
2021-03-29 17:49 ` Uwe Kleine-König
2021-03-29 12:57 ` [PATCH v6 7/7] pwm: pca9685: Add error messages for failed regmap calls Clemens Gruber
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