linux-kernel - Re: [PATCH] media: cedrus: Add watchdog for job completion

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Message-ID: <20220205102853.54wcmxzalb7uj7n6@houat>
Date:   Sat, 5 Feb 2022 11:28:53 +0100
From:   Maxime Ripard <maxime@...no.tech>
To:     Jernej Škrabec <jernej.skrabec@...il.com>
Cc:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        mchehab@...nel.org, wens@...e.org, linux-media@...r.kernel.org,
        linux-staging@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: cedrus: Add watchdog for job completion

On Sat, Feb 05, 2022 at 08:40:21AM +0100, Jernej Škrabec wrote:
> > > +void cedrus_watchdog(struct work_struct *work)
> > > +{
> > > +	struct cedrus_dev *dev;
> > > +	struct cedrus_ctx *ctx;
> > > +
> > > +	dev = container_of(to_delayed_work(work),
> > > +			   struct cedrus_dev, watchdog_work);
> > > +
> > > +	ctx = v4l2_m2m_get_curr_priv(dev->m2m_dev);
> > > +	if (!ctx)
> > > +		return;
> > > +
> > > +	v4l2_err(&dev->v4l2_dev, "frame processing timed out!\n");
> > > +	reset_control_reset(dev->rstc);
> > 
> > I don't think playing with the reset is the right approach here.
> > First we don't really know if the reset is shared or not, so this might have
> > no effect.
> 
> AFAIK only few reset lines are shared in all Allwinner SoC, never for Cedrus 
> and even then, this is considered as HW issue. So, I'm good with using reset 
> line. This principle is also taken from Hantro driver.

Also, we got the reset handle through reset_control_get_exclusive, so
we're guaranteed to be the only user.

Maxime