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Subject: Re: [PATCH RFT v1 3/3] drm/panfrost: Use the mali-supply regulator
 for control again
To:     Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        dri-devel@lists.freedesktop.org, alyssa@rosenzweig.io,
        tomeu.vizoso@collabora.com, robh@kernel.org
Cc:     airlied@linux.ie, linux-kernel@vger.kernel.org,
        linux-rockchip@lists.infradead.org,
        linux-amlogic@lists.infradead.org, robin.murphy@arm.com
References: <20200107230626.885451-1-martin.blumenstingl@googlemail.com>
 <20200107230626.885451-4-martin.blumenstingl@googlemail.com>
From:   Steven Price <steven.price@arm.com>
Message-ID: <2ceffe46-57a8-79a8-2c41-d04b227d3792@arm.com>
Date:   Thu, 9 Jan 2020 11:31:48 +0000
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On 07/01/2020 23:06, Martin Blumenstingl wrote:
> dev_pm_opp_set_rate() needs a reference to the regulator which should be
> updated when updating the GPU frequency. The name of the regulator has
> to be passed at initialization-time using dev_pm_opp_set_regulators().
> Add the call to dev_pm_opp_set_regulators() so dev_pm_opp_set_rate()
> will update the GPU regulator when updating the frequency (just like
> we did this manually before when we open-coded dev_pm_opp_set_rate()).

This patch causes a warning from debugfs on my firefly (RK3288) board:

debugfs: Directory 'ffa30000.gpu-mali' with parent 'vdd_gpu' already
present!

So it looks like the regulator is being added twice - but I haven't
investigated further.

> Fixes: 221bc77914cbcc ("drm/panfrost: Use generic code for devfreq")
> Reported-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> ---
>  drivers/gpu/drm/panfrost/panfrost_devfreq.c | 22 ++++++++++++++++++++-
>  drivers/gpu/drm/panfrost/panfrost_device.h  |  1 +
>  2 files changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> index 170f6c8c9651..4f7999c7b44c 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> @@ -74,6 +74,7 @@ static struct devfreq_dev_profile panfrost_devfreq_profile = {
>  int panfrost_devfreq_init(struct panfrost_device *pfdev)
>  {
>  	int ret;
> +	struct opp_table *opp_table;
>  	struct dev_pm_opp *opp;
>  	unsigned long cur_freq;
>  	struct device *dev = &pfdev->pdev->dev;
> @@ -84,9 +85,24 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
>  		/* Optional, continue without devfreq */
>  		return 0;
>  
> +	opp_table = dev_pm_opp_set_regulators(dev,
> +					      (const char *[]){ "mali" },
> +					      1);
> +	if (IS_ERR(opp_table)) {
> +		ret = PTR_ERR(opp_table);
> +
> +		/* Continue if the optional regulator is missing */
> +		if (ret != -ENODEV)
> +			return ret;
> +	} else {
> +		pfdev->devfreq.regulators_opp_table = opp_table;
> +	}
> +
>  	ret = dev_pm_opp_of_add_table(dev);
> -	if (ret)
> +	if (ret) {
> +		dev_pm_opp_put_regulators(pfdev->devfreq.regulators_opp_table);

If we don't have a regulator then regulators_opp_table will be NULL and
sadly dev_pm_opp_put_regulators() doesn't handle a NULL argument. The
same applies to the two below calls obviously.

Steve

>  		return ret;
> +	}
>  
>  	panfrost_devfreq_reset(pfdev);
>  
> @@ -95,6 +111,7 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
>  	opp = devfreq_recommended_opp(dev, &cur_freq, 0);
>  	if (IS_ERR(opp)) {
>  		dev_pm_opp_of_remove_table(dev);
> +		dev_pm_opp_put_regulators(pfdev->devfreq.regulators_opp_table);
>  		return PTR_ERR(opp);
>  	}
>  
> @@ -106,6 +123,7 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
>  	if (IS_ERR(devfreq)) {
>  		DRM_DEV_ERROR(dev, "Couldn't initialize GPU devfreq\n");
>  		dev_pm_opp_of_remove_table(dev);
> +		dev_pm_opp_put_regulators(pfdev->devfreq.regulators_opp_table);
>  		return PTR_ERR(devfreq);
>  	}
>  	pfdev->devfreq.devfreq = devfreq;
> @@ -124,6 +142,8 @@ void panfrost_devfreq_fini(struct panfrost_device *pfdev)
>  	if (pfdev->devfreq.cooling)
>  		devfreq_cooling_unregister(pfdev->devfreq.cooling);
>  	dev_pm_opp_of_remove_table(&pfdev->pdev->dev);
> +	if (pfdev->devfreq.regulators_opp_table)
> +		dev_pm_opp_put_regulators(pfdev->devfreq.regulators_opp_table);
>  }
>  
>  void panfrost_devfreq_resume(struct panfrost_device *pfdev)
> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
> index 06713811b92c..4878b239e301 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_device.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_device.h
> @@ -85,6 +85,7 @@ struct panfrost_device {
>  
>  	struct {
>  		struct devfreq *devfreq;
> +		struct opp_table *regulators_opp_table;
>  		struct thermal_cooling_device *cooling;
>  		ktime_t busy_time;
>  		ktime_t idle_time;
>