linux-kernel - Re: [PATCH v5 3/5] remoteproc: Add prepare/unprepare callbacks

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Message-ID: <daf58c35-c240-e50a-da50-48b14c0e097c@st.com>
Date:   Tue, 18 Feb 2020 17:31:30 +0100
From:   Arnaud POULIQUEN <arnaud.pouliquen@...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>, <linux-remoteproc@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 3/5] remoteproc: Add prepare/unprepare callbacks

Hi Paul,

I still wonder about the use of pm_runtime mechanism as a more generic alternative...

Else just a minor remark inline.

On 2/11/20 3:26 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.
> 
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
> 
> Notes:
>     v2-v4: No change
>     v5: Move calls to prepare/unprepare to rproc_fw_boot/rproc_shutdown
> 
>  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 fe5c7a2f9767..022b927e176b 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1373,6 +1373,14 @@ static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
>  
>  	dev_info(dev, "Booting fw image %s, size %zd\n", name, fw->size);
>  
> +	if (rproc->ops->prepare) {
> +		ret = rproc->ops->prepare(rproc);
> +		if (ret) {
> +			dev_err(dev, "Failed to prepare rproc: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
>  	/*
>  	 * if enabling an IOMMU isn't relevant for this rproc, this is
>  	 * just a nop
> @@ -1380,7 +1388,7 @@ static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
>  	ret = rproc_enable_iommu(rproc);
>  	if (ret) {
>  		dev_err(dev, "can't enable iommu: %d\n", ret);
> -		return ret;
> +		goto unprepare_rproc;
>  	}
>  
>  	rproc->bootaddr = rproc_get_boot_addr(rproc, fw);
> @@ -1424,6 +1432,9 @@ static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
>  	rproc->table_ptr = NULL;
>  disable_iommu:
>  	rproc_disable_iommu(rproc);
> +unprepare_rproc:
> +	if (rproc->ops->unprepare)
> +		rproc->ops->unprepare(rproc);
>  	return ret;
>  }
>  
> @@ -1823,6 +1834,9 @@ void rproc_shutdown(struct rproc *rproc)
>  
>  	rproc_disable_iommu(rproc);
>  
> +	if (rproc->ops->unprepare)
> +		rproc->ops->unprepare(rproc);
> +
>  	/* Free the copy of the resource table */
>  	kfree(rproc->cached_table);
>  	rproc->cached_table = NULL;
> 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

Would be nice here to precise that these functions are optional
you can look at rproc_ops struct for example.

Regards,
Arnaud

>   * @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);
>