linux-kernel - Re: [PATCH] drm/panfrost: Add missing OPP table refcnt decremental

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Message-ID: <20241003091740.4e610f21@collabora.com>
Date: Thu, 3 Oct 2024 09:17:40 +0200
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Adrián Larumbe <adrian.larumbe@...labora.com>
Cc: Rob Herring <robh@...nel.org>, Steven Price <steven.price@....com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
 <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
 <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, AngeloGioacchino Del
 Regno <angelogioacchino.delregno@...labora.com>, kernel@...labora.com,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/panfrost: Add missing OPP table refcnt decremental

On Thu,  3 Oct 2024 01:25:37 +0100
Adrián Larumbe <adrian.larumbe@...labora.com> wrote:

> Commit f11b0417eec2 ("drm/panfrost: Add fdinfo support GPU load metrics")
> retrieves the OPP for the maximum device clock frequency, but forgets to
> keep the reference count balanced by putting the returned OPP object. This
> eventually leads to an OPP core warning when removing the device.
> 
> Fix it by putting OPP objects as many times as they're retrieved.
> Also remove an unnecessary whitespace.
> 
> Signed-off-by: Adrián Larumbe <adrian.larumbe@...labora.com>
> Fixes: f11b0417eec2 ("drm/panfrost: Add fdinfo support GPU load metrics")

Reviewed-by: 

> ---
>  drivers/gpu/drm/panfrost/panfrost_devfreq.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> index 2d30da38c2c3..c7d3f980f1e5 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> @@ -38,7 +38,7 @@ static int panfrost_devfreq_target(struct device *dev, unsigned long *freq,
>  		return PTR_ERR(opp);
>  	dev_pm_opp_put(opp);
>  
> -	err =  dev_pm_opp_set_rate(dev, *freq);
> +	err = dev_pm_opp_set_rate(dev, *freq);
>  	if (!err)
>  		ptdev->pfdevfreq.current_frequency = *freq;
>  
> @@ -177,6 +177,8 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
>  	 */
>  	pfdevfreq->current_frequency = cur_freq;
>  
> +	dev_pm_opp_put(opp);
> +

Shouldn't this be moved after the dev_pm_opp_set_opp() that's
following?

>  	/*
>  	 * Set the recommend OPP this will enable and configure the regulator
>  	 * if any and will avoid a switch off by regulator_late_cleanup()