linux-kernel - Re: [PATCH 5/5] remoteproc: Introduce prepare and unprepare for subdevices

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Date:   Tue, 29 May 2018 11:16:20 +0200
From:   Arnaud Pouliquen <arnaud.pouliquen@...com>
To:     Alex Elder <elder@...aro.org>, <ohad@...ery.com>,
        <bjorn.andersson@...aro.org>
CC:     <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/5] remoteproc: Introduce prepare and unprepare for
 subdevices

Hello Alex,


On 05/15/2018 10:53 PM, Alex Elder wrote:
> From: Bjorn Andersson <bjorn.andersson@...aro.org>
> 
> On rare occasions a subdevice might need to prepare some hardware
> resources before a remote processor is booted, and clean up some
> state after it has been shut down.
> 
> One such example is the IP Accelerator found in various Qualcomm
> platforms, which is accessed directly from both the modem remoteproc
> and the application subsystem and requires an intricate lockstep
> process when bringing the modem up and down.
> 
> [elder@...aro.org: minor description and comment edits]
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> Acked-by: Alex Elder <elder@...aro.org>
> ---
>  drivers/remoteproc/remoteproc_core.c | 56 ++++++++++++++++++++++++++--
>  include/linux/remoteproc.h           |  4 ++
>  2 files changed, 57 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 2ede7ae6f5bc..283b258f5e0f 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -776,6 +776,30 @@ static int rproc_handle_resources(struct rproc *rproc,
>  	return ret;
>  }
>  
> +static int rproc_prepare_subdevices(struct rproc *rproc)
> +{
> +	struct rproc_subdev *subdev;
> +	int ret;
> +
> +	list_for_each_entry(subdev, &rproc->subdevs, node) {
> +		if (subdev->prepare) {
> +			ret = subdev->prepare(subdev);
> +			if (ret)
> +				goto unroll_preparation;
> +		}
> +	}
> +
> +	return 0;
> +
> +unroll_preparation:
> +	list_for_each_entry_continue_reverse(subdev, &rproc->subdevs, node) {
> +		if (subdev->unprepare)
> +			subdev->unprepare(subdev);
> +	}
Here you could call rproc_unprepare_subdevices instead of duplicating
the code.

regards
Arnaud
> +
> +	return ret;
> +}
> +
>  static int rproc_start_subdevices(struct rproc *rproc)
>  {
>  	struct rproc_subdev *subdev;
> @@ -810,6 +834,16 @@ static void rproc_stop_subdevices(struct rproc *rproc, bool crashed)
>  	}
>  }
>  
> +static void rproc_unprepare_subdevices(struct rproc *rproc)
> +{
> +	struct rproc_subdev *subdev;
> +
> +	list_for_each_entry_reverse(subdev, &rproc->subdevs, node) {
> +		if (subdev->unprepare)
> +			subdev->unprepare(subdev);
> +	}
> +}
> +
>  /**
>   * rproc_coredump_cleanup() - clean up dump_segments list
>   * @rproc: the remote processor handle
> @@ -902,11 +936,18 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
>  		rproc->table_ptr = loaded_table;
>  	}
>  
> +	ret = rproc_prepare_subdevices(rproc);
> +	if (ret) {
> +		dev_err(dev, "failed to prepare subdevices for %s: %d\n",
> +			rproc->name, ret);
> +		return ret;
> +	}
> +
>  	/* power up the remote processor */
>  	ret = rproc->ops->start(rproc);
>  	if (ret) {
>  		dev_err(dev, "can't start rproc %s: %d\n", rproc->name, ret);
> -		return ret;
> +		goto unprepare_subdevices;
>  	}
>  
>  	/* Start any subdevices for the remote processor */
> @@ -914,8 +955,7 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
>  	if (ret) {
>  		dev_err(dev, "failed to probe subdevices for %s: %d\n",
>  			rproc->name, ret);
> -		rproc->ops->stop(rproc);
> -		return ret;
> +		goto stop_rproc;
>  	}
>  
>  	rproc->state = RPROC_RUNNING;
> @@ -923,6 +963,14 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
>  	dev_info(dev, "remote processor %s is now up\n", rproc->name);
>  
>  	return 0;
> +
> +stop_rproc:
> +	rproc->ops->stop(rproc);
> +
> +unprepare_subdevices:
> +	rproc_unprepare_subdevices(rproc);
> +
> +	return ret;
>  }
>  
>  /*
> @@ -1035,6 +1083,8 @@ static int rproc_stop(struct rproc *rproc, bool crashed)
>  		return ret;
>  	}
>  
> +	rproc_unprepare_subdevices(rproc);
> +
>  	rproc->state = RPROC_OFFLINE;
>  
>  	dev_info(dev, "stopped remote processor %s\n", rproc->name);
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index 8f1426330cca..e3c5d856b6da 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -477,15 +477,19 @@ struct rproc {
>  /**
>   * struct rproc_subdev - subdevice tied to a remoteproc
>   * @node: list node related to the rproc subdevs list
> + * @prepare: prepare function, called before the rproc is started
>   * @start: start function, called after the rproc has been started
>   * @stop: stop function, called before the rproc is stopped; the @crashed
>   *	    parameter indicates if this originates from a recovery
> + * @unprepare: unprepare function, called after the rproc has been stopped
>   */
>  struct rproc_subdev {
>  	struct list_head node;
>  
> +	int (*prepare)(struct rproc_subdev *subdev);
>  	int (*start)(struct rproc_subdev *subdev);
>  	void (*stop)(struct rproc_subdev *subdev, bool crashed);
> +	void (*unprepare)(struct rproc_subdev *subdev);
>  };
>  
>  /* we currently support only two vrings per rvdev */
>