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

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Message-ID: <e33rx3l52arkfgno64l5dctibo647kx3cpjlwcm3lil6cvszrt@abhg2mbu7ec4>
Date: Thu, 3 Oct 2024 12:38:26 +0100
From: Adrián Larumbe <adrian.larumbe@...labora.com>
To: Boris Brezillon <boris.brezillon@...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 03.10.2024 09:17, Boris Brezillon wrote:
> 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?

Yes, right now it's in the wrong place, thanks for catching this.

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


Adrian Larumbe