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Subject: Re: [PATCH v4 11/17] remoteproc: Introduce function __rproc_detach()
To:     Mathieu Poirier <mathieu.poirier@linaro.org>,
        "ohad@wizery.com" <ohad@wizery.com>,
        "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>
CC:     "linux-remoteproc@vger.kernel.org" <linux-remoteproc@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20201218173228.2277032-1-mathieu.poirier@linaro.org>
 <20201218173228.2277032-12-mathieu.poirier@linaro.org>
From:   Arnaud POULIQUEN <arnaud.pouliquen@st.com>
Message-ID: <5419749d-5e81-8b0c-616f-e0d5e237ac9a@st.com>
Date:   Wed, 27 Jan 2021 09:46:58 +0100
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On 12/18/20 6:32 PM, Mathieu Poirier wrote:
> Introduce function __rproc_detach() to perform the same kind of
> operation as rproc_stop(), but instead of switching off the
> remote processor using rproc->ops->stop(), it uses
> rproc->ops->detach().  That way it is possible for the core
> to release the resources associated with a remote processor while
> the latter is kept operating.
> 
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> Reviewed-by: Peng Fan <peng.fan@nxp.com>
> ---
>  drivers/remoteproc/remoteproc_core.c | 42 ++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index fc28053c7f89..e665ed4776c3 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1670,6 +1670,48 @@ static int rproc_stop(struct rproc *rproc, bool crashed)
>  	return 0;
>  }
>  
> +/*
> + * __rproc_detach(): Does the opposite of rproc_attach()
> + */
> +static int __maybe_unused __rproc_detach(struct rproc *rproc)
> +{
> +	struct device *dev = &rproc->dev;
> +	int ret;
> +
> +	/* No need to continue if a detach() operation has not been provided */
> +	if (!rproc->ops->detach)
> +		return -EINVAL;

I wonder if this ops should be optional.

> +
> +	/* Stop any subdevices for the remote processor */
> +	rproc_stop_subdevices(rproc, false);
> +
> +	/*
> +	 * If the remote processors was started by the core then a cached_table
> +	 * is present and we must follow the same cleanup sequence as we would
> +	 * for a shutdown().  As it is in rproc_stop(), use the cached resource
> +	 * table for the rest of the detach process since ->table_ptr will
> +	 * become invalid as soon as carveouts are released in
> +	 * rproc_resource_cleanup().
> +	 */
> +	if (rproc->cached_table)
> +		rproc->table_ptr = rproc->cached_table;
> +
> +	/* Tell the remote processor the core isn't available anymore */
> +	ret = rproc->ops->detach(rproc);
> +	if (ret) {
> +		dev_err(dev, "can't detach from rproc: %d\n", ret);
> +		rproc_start_subdevices(rproc);

Not sure that this would be possible in all cases, without a unprepare and
prepare. What about having the same behavior as the rproc_stop failure?

Thanks
Arnaud.

> +		return ret;
> +	}
> +
> +	rproc_unprepare_subdevices(rproc);
> +
> +	rproc->state = RPROC_DETACHED;
> +
> +	dev_info(dev, "detached remote processor %s\n", rproc->name);
> +
> +	return 0;
> +}
>  
>  /**
>   * rproc_trigger_recovery() - recover a remoteproc
>