Re: [PATCH v6 10/16] remoteproc: Introduce function rproc_detach()

[Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>]

On 2/24/21 12:35 AM, Mathieu Poirier wrote:
> Introduce function rproc_detach() to enable the remoteproc
> core to release the resources associated with a remote processor
> without stopping its operation.
> 
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

Reviewed-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>

Thanks,

> ---
> New for V6:
> - Checking for rproc->state has been removed.  They have been moved to
>   calling functions.
> - Freeing the cache table has been moved to the next patch, i.e 11/16.
> ---
> 
>  drivers/remoteproc/remoteproc_core.c | 58 +++++++++++++++++++++++++++-
>  include/linux/remoteproc.h           |  1 +
>  2 files changed, 58 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 0f680b7ff8f1..fc01b29290a6 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1709,7 +1709,7 @@ static int rproc_stop(struct rproc *rproc, bool crashed)
>  /*
>   * __rproc_detach(): Does the opposite of __rproc_attach()
>   */
> -static int __maybe_unused __rproc_detach(struct rproc *rproc)
> +static int __rproc_detach(struct rproc *rproc)
>  {
>  	struct device *dev = &rproc->dev;
>  	int ret;
> @@ -1948,6 +1948,62 @@ void rproc_shutdown(struct rproc *rproc)
>  }
>  EXPORT_SYMBOL(rproc_shutdown);
>  
> +/**
> + * rproc_detach() - Detach the remote processor from the
> + * remoteproc core
> + *
> + * @rproc: the remote processor
> + *
> + * Detach a remote processor (previously attached to with rproc_attach()).
> + *
> + * In case @rproc is still being used by an additional user(s), then
> + * this function will just decrement the power refcount and exit,
> + * without disconnecting the device.
> + *
> + * Function rproc_detach() calls __rproc_detach() in order to let a remote
> + * processor know that services provided by the application processor are
> + * no longer available.  From there it should be possible to remove the
> + * platform driver and even power cycle the application processor (if the HW
> + * supports it) without needing to switch off the remote processor.
> + */
> +int rproc_detach(struct rproc *rproc)
> +{
> +	struct device *dev = &rproc->dev;
> +	int ret;
> +
> +	ret = mutex_lock_interruptible(&rproc->lock);
> +	if (ret) {
> +		dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, ret);
> +		return ret;
> +	}
> +
> +	/* if the remote proc is still needed, bail out */
> +	if (!atomic_dec_and_test(&rproc->power)) {
> +		ret = 0;
> +		goto out;
> +	}
> +
> +	ret = __rproc_detach(rproc);
> +	if (ret) {
> +		atomic_inc(&rproc->power);
> +		goto out;
> +	}
> +
> +	/* clean up all acquired resources */
> +	rproc_resource_cleanup(rproc);
> +
> +	/* release HW resources if needed */
> +	rproc_unprepare_device(rproc);
> +
> +	rproc_disable_iommu(rproc);
> +
> +	rproc->table_ptr = NULL;
> +out:
> +	mutex_unlock(&rproc->lock);
> +	return ret;
> +}
> +EXPORT_SYMBOL(rproc_detach);
> +
>  /**
>   * rproc_get_by_phandle() - find a remote processor by phandle
>   * @phandle: phandle to the rproc
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index eff55ec72e80..e1c843c19cc6 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -662,6 +662,7 @@ rproc_of_resm_mem_entry_init(struct device *dev, u32 of_resm_idx, size_t len,
>  
>  int rproc_boot(struct rproc *rproc);
>  void rproc_shutdown(struct rproc *rproc);
> +int rproc_detach(struct rproc *rproc);
>  int rproc_set_firmware(struct rproc *rproc, const char *fw_name);
>  void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type);
>  void rproc_coredump_using_sections(struct rproc *rproc);
>