linux-kernel - Re: [PATCH v4 3/5] remoteproc: Add prepare/unprepare callbacks

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Date:   Thu, 12 Dec 2019 10:03:29 +0000
From:   Fabien DESSENNE <fabien.dessenne@...com>
To:     Paul Cercueil <paul@...pouillou.net>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>
CC:     "od@...c.me" <od@...c.me>,
        "linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 3/5] remoteproc: Add prepare/unprepare callbacks

Hi Paul


On 10/12/2019 5:40 PM, Paul Cercueil wrote:
> The .prepare() callback is called before the firmware is loaded to
> memory. This is useful for instance in the case where some setup is
> required for the memory to be accessible.


I am trying to figure out what king of 'setup' may be required. From the 
ingenic driver I understand that you need to enable clocks to allow some 
memory access.

Instead of adding this new ops, why not enabling clocks in probe()?

BR

Fabien


>
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
>
> Notes:
>      v2-v4: No change
>
>   drivers/remoteproc/remoteproc_core.c | 16 +++++++++++++++-
>   include/linux/remoteproc.h           |  4 ++++
>   2 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 0a9fc7fdd1c3..3ea5f675a148 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1299,11 +1299,19 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
>   	struct device *dev = &rproc->dev;
>   	int ret;
>   
> +	if (rproc->ops->prepare) {
> +		ret = rproc->ops->prepare(rproc);
> +		if (ret) {
> +			dev_err(dev, "Failed to prepare rproc: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
>   	/* load the ELF segments to memory */
>   	ret = rproc_load_segments(rproc, fw);
>   	if (ret) {
>   		dev_err(dev, "Failed to load program segments: %d\n", ret);
> -		return ret;
> +		goto unprepare_rproc;
>   	}
>   
>   	/*
> @@ -1354,6 +1362,9 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
>   	rproc_unprepare_subdevices(rproc);
>   reset_table_ptr:
>   	rproc->table_ptr = rproc->cached_table;
> +unprepare_rproc:
> +	if (rproc->ops->unprepare)
> +		rproc->ops->unprepare(rproc);
>   
>   	return ret;
>   }
> @@ -1483,6 +1494,9 @@ static int rproc_stop(struct rproc *rproc, bool crashed)
>   
>   	rproc->state = RPROC_OFFLINE;
>   
> +	if (rproc->ops->unprepare)
> +		rproc->ops->unprepare(rproc);
> +
>   	dev_info(dev, "stopped remote processor %s\n", rproc->name);
>   
>   	return 0;
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index 5f201f0c86c3..a6272d1ba384 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -355,6 +355,8 @@ enum rsc_handling_status {
>   
>   /**
>    * struct rproc_ops - platform-specific device handlers
> + * @prepare:	prepare the device for power up (before the firmware is loaded)
> + * @unprepare:	unprepare the device after it is stopped
>    * @start:	power on the device and boot it
>    * @stop:	power off the device
>    * @kick:	kick a virtqueue (virtqueue id given as a parameter)
> @@ -371,6 +373,8 @@ enum rsc_handling_status {
>    * @get_boot_addr:	get boot address to entry point specified in firmware
>    */
>   struct rproc_ops {
> +	int (*prepare)(struct rproc *rproc);
> +	void (*unprepare)(struct rproc *rproc);
>   	int (*start)(struct rproc *rproc);
>   	int (*stop)(struct rproc *rproc);
>   	void (*kick)(struct rproc *rproc, int vqid);