linux-kernel - Re: [PATCH v4 2/9] remoteproc: Add new attach() remoteproc operation

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Date:   Sun, 21 Jun 2020 23:36:38 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     ohad@...ery.com, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org, loic.pallardy@...com,
        arnaud.pouliquen@...com, s-anna@...com
Subject: Re: [PATCH v4 2/9] remoteproc: Add new attach() remoteproc operation

On Mon 01 Jun 10:51 PDT 2020, Mathieu Poirier wrote:

> Add an new attach() operation in order to properly deal with
> scenarios where the remoteproc core needs to attach to a
> remote processor that has been booted by another entity.
> 
> Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> ---
>  drivers/remoteproc/remoteproc_internal.h | 8 ++++++++
>  include/linux/remoteproc.h               | 2 ++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/drivers/remoteproc/remoteproc_internal.h b/drivers/remoteproc/remoteproc_internal.h
> index 4ba7cb59d3e8..fc710866f8ce 100644
> --- a/drivers/remoteproc/remoteproc_internal.h
> +++ b/drivers/remoteproc/remoteproc_internal.h
> @@ -79,6 +79,14 @@ static inline int rproc_unprepare_device(struct rproc *rproc)
>  	return 0;
>  }
>  
> +static inline int rproc_attach_device(struct rproc *rproc)
> +{
> +	if (rproc->ops->attach)
> +		return rproc->ops->attach(rproc);
> +
> +	return 0;

Afaict we don't allow the registration of a remoteproc in DETACHED state
without an "attach" function specified and as such we shouldn't be able
to end up here.

On the other hand I think it would make sense to have a system where
"attach" simply just means bring up the communication with the remote
processor, so let's keep it as is and we can adjust it as necessary
later.

Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>

Regards,
Bjorn

> +}
> +
>  static inline
>  int rproc_fw_sanity_check(struct rproc *rproc, const struct firmware *fw)
>  {
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index 21182ad2d059..bf6a310ba870 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -359,6 +359,7 @@ enum rsc_handling_status {
>   * @unprepare:	unprepare device after stop
>   * @start:	power on the device and boot it
>   * @stop:	power off the device
> + * @attach:	attach to a device that his already powered up
>   * @kick:	kick a virtqueue (virtqueue id given as a parameter)
>   * @da_to_va:	optional platform hook to perform address translations
>   * @parse_fw:	parse firmware to extract information (e.g. resource table)
> @@ -379,6 +380,7 @@ struct rproc_ops {
>  	int (*unprepare)(struct rproc *rproc);
>  	int (*start)(struct rproc *rproc);
>  	int (*stop)(struct rproc *rproc);
> +	int (*attach)(struct rproc *rproc);
>  	void (*kick)(struct rproc *rproc, int vqid);
>  	void * (*da_to_va)(struct rproc *rproc, u64 da, size_t len);
>  	int (*parse_fw)(struct rproc *rproc, const struct firmware *fw);
> -- 
> 2.20.1
>