Linux-ARM-Kernel Archive on lore.kernel.org
 help / color / Atom feed
From: Fabrice Gasnier <fabrice.gasnier@st.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: mark.rutland@arm.com, devicetree@vger.kernel.org,
	alexandre.torgue@st.com, tduszyns@gmail.com,
	linux-kernel@vger.kernel.org, robh+dt@kernel.org,
	thierry.reding@gmail.com, linux-pwm@vger.kernel.org,
	mcoquelin.stm32@gmail.com,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 3/3] pwm: core: add consumer device link
Date: Tue, 12 Feb 2019 09:31:37 +0100
Message-ID: <b9f1bb5c-36cd-f6e6-e6c6-a0257cf38b7e@st.com> (raw)
In-Reply-To: <20190211190628.eisyi6wjus4ltrrn@pengutronix.de>

On 2/11/19 8:06 PM, Uwe Kleine-König wrote:
> Hello Fabrice,
> 
> On Mon, Feb 11, 2019 at 05:12:02PM +0100, Fabrice Gasnier wrote:
>> Add a device link between the PWM consumer and the PWM provider. This
>> enforces the PWM user to get suspended before the PWM provider. It
>> allows proper synchronization of suspend/resume sequences: the PWM user
>> is responsible for properly stopping PWM, before the provider gets
>> suspended: see [1]. Add the device link in:
>> - pwm_get()
>> - devm_pwm_get()
>> - devm_of_pwm_get()
>> as it requires a reference to the device for the PWM consumer.
>>
>> [1] https://lkml.org/lkml/2019/2/5/770
>>
>> Suggested-by: Thierry Reding <thierry.reding@gmail.com>
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
>> ---
>>  drivers/pwm/core.c | 13 +++++++++++--
>>  1 file changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
>> index 1581f6a..2835e27 100644
>> --- a/drivers/pwm/core.c
>> +++ b/drivers/pwm/core.c
>> @@ -770,8 +770,13 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
>>  	int err;
>>  
>>  	/* look up via DT first */
>> -	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
>> -		return of_pwm_get(dev->of_node, con_id);
>> +	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) {
>> +		pwm = of_pwm_get(dev->of_node, con_id);
>> +		if (!IS_ERR(pwm))
>> +			device_link_add(dev, pwm->chip->dev,
>> +					DL_FLAG_AUTOREMOVE_CONSUMER);
>> +		return pwm;
>> +	}
>>  
>>  	/*
>>  	 * We look up the provider in the static table typically provided by
>> @@ -851,6 +856,8 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
>>  	pwm->args.period = chosen->period;
>>  	pwm->args.polarity = chosen->polarity;
>>  
>> +	device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER);
>> +
>>  	return pwm;
>>  }
>>  EXPORT_SYMBOL_GPL(pwm_get);
>> @@ -943,6 +950,8 @@ struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
>>  	if (!IS_ERR(pwm)) {
>>  		*ptr = pwm;
>>  		devres_add(dev, ptr);
>> +		device_link_add(dev, pwm->chip->dev,
>> +				DL_FLAG_AUTOREMOVE_CONSUMER);
> 
> IMHO it's surprising that devm_of_pwm_get() does more than of_pwm_get()
> + devres stuff. I'd put device_link_add() into of_pwm_get().

Hi Uwe,

I also agree with this. But I think this implies modifying the API for
of_pwm_get():
 /**
  * of_pwm_get() - request a PWM via the PWM framework
+ * @dev: device for PWM consumer
  * @np: device node to get the PWM from
  * @con_id: consumer name

It seems there aren't much of_pwm_get() users currently.
Does this look sensible ?

Best regards,
Fabrice

> 
> Best regards
> Uwe
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-11 16:11 [PATCH v2 0/3] Add PM support to STM32 LP Timer drivers Fabrice Gasnier
2019-02-11 16:12 ` [PATCH v2 1/3] dt-bindings: pwm-stm32-lp: document pinctrl sleep state Fabrice Gasnier
2019-02-11 16:12 ` [PATCH v2 2/3] pwm: stm32-lp: Add power management support Fabrice Gasnier
2019-02-11 16:12 ` [PATCH v2 3/3] pwm: core: add consumer device link Fabrice Gasnier
2019-02-11 19:06   ` Uwe Kleine-König
2019-02-12  8:31     ` Fabrice Gasnier [this message]
2019-02-12  9:03       ` Uwe Kleine-König
2019-02-13 10:51         ` Fabrice Gasnier

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=b9f1bb5c-36cd-f6e6-e6c6-a0257cf38b7e@st.com \
    --to=fabrice.gasnier@st.com \
    --cc=alexandre.torgue@st.com \
    --cc=devicetree@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pwm@vger.kernel.org \
    --cc=linux-stm32@st-md-mailman.stormreply.com \
    --cc=mark.rutland@arm.com \
    --cc=mcoquelin.stm32@gmail.com \
    --cc=robh+dt@kernel.org \
    --cc=tduszyns@gmail.com \
    --cc=thierry.reding@gmail.com \
    --cc=u.kleine-koenig@pengutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ARM-Kernel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-arm-kernel/0 linux-arm-kernel/git/0.git
	git clone --mirror https://lore.kernel.org/linux-arm-kernel/1 linux-arm-kernel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-arm-kernel linux-arm-kernel/ https://lore.kernel.org/linux-arm-kernel \
		linux-arm-kernel@lists.infradead.org infradead-linux-arm-kernel@archiver.kernel.org
	public-inbox-index linux-arm-kernel


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-arm-kernel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox