Re: [PATCH v10 01/11] PM / devfreq: Fix devfreq_notifier_call returning errno

From: Chanwoo Choi <cw00.choi@samsung•com>
To: Leonard Crestez <leonard.crestez@nxp•com>,
	MyungJoo Ham <myungjoo.ham@samsung•com>,
	Kyungmin Park <kyungmin.park@samsung•com>,
	"Rafael J. Wysocki" <rjw@rjwysocki•net>
Cc: "Artur Świgoń" <a.swigon@partner•samsung.com>,
	"Abel Vesa" <abel.vesa@nxp•com>,
	"Saravana Kannan" <saravanak@google•com>,
	linux-pm@vger•kernel.org,
	"Viresh Kumar" <viresh.kumar@linaro•org>,
	"NXP Linux Team" <linux-imx@nxp•com>,
	"Krzysztof Kozlowski" <krzk@kernel•org>,
	"Matthias Kaehlcke" <mka@chromium•org>,
	"Alexandre Bailon" <abailon@baylibre•com>,
	"Georgi Djakov" <georgi.djakov@linaro•org>,
	linux-arm-kernel@lists•infradead.org,
	"Jacky Bai" <ping.bai@nxp•com>
Subject: Re: [PATCH v10 01/11] PM / devfreq: Fix devfreq_notifier_call returning errno
Date: Mon, 11 Nov 2019 14:55:25 +0900	[thread overview]
Message-ID: <3e31fce5-97ec-5f69-d352-d45a7cf0eb75@samsung.com> (raw)
In-Reply-To: <b13007563e6c1e29e2d9b31c9881693fc2bf167a.1572556786.git.leonard.crestez@nxp.com>

On 11/1/19 6:34 AM, Leonard Crestez wrote:
> Notifier callbacks shouldn't return negative errno but one of the
> NOTIFY_OK/DONE/BAD values.
> 
> The OPP core will ignore return values from notifiers but returning a
> value that matches NOTIFY_STOP_MASK will stop the notification chain.
> 
> Fix by always returning NOTIFY_OK.
> 
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp•com>
> Reviewed-by: Matthias Kaehlcke <mka@chromium•org>
> Reviewed-by: Chanwoo Choi <cw00.choi@samsung•com>
> ---
>  drivers/devfreq/devfreq.c | 24 +++++++++++++-----------
>  1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 323d43315d1e..b65faa1a2baa 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -548,30 +548,32 @@ EXPORT_SYMBOL(devfreq_interval_update);
>   */
>  static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
>  				 void *devp)
>  {
>  	struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
> -	int ret;
> +	int err = -EINVAL;
>  
>  	mutex_lock(&devfreq->lock);
>  
>  	devfreq->scaling_min_freq = find_available_min_freq(devfreq);
> -	if (!devfreq->scaling_min_freq) {
> -		mutex_unlock(&devfreq->lock);
> -		return -EINVAL;
> -	}
> +	if (!devfreq->scaling_min_freq)
> +		goto out;
>  
>  	devfreq->scaling_max_freq = find_available_max_freq(devfreq);
> -	if (!devfreq->scaling_max_freq) {
> -		mutex_unlock(&devfreq->lock);
> -		return -EINVAL;
> -	}
> +	if (!devfreq->scaling_max_freq)
> +		goto out;
> +
> +	err = update_devfreq(devfreq);
>  
> -	ret = update_devfreq(devfreq);
> +out:
>  	mutex_unlock(&devfreq->lock);
> +	if (err)
> +		dev_err(devfreq->dev.parent,
> +			"failed to update frequency from OPP notifier (%d)\n",
> +			err);
>  
> -	return ret;
> +	return NOTIFY_OK;
>  }
>  
>  /**
>   * devfreq_dev_release() - Callback for struct device to release the device.
>   * @dev:	the devfreq device
> 

Applied it because it doesn't depend on the pm_qos feature.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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