linux-kernel - RE: [PATCH 07/13] remoteproc: Introduce function rproc

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Date:   Thu, 15 Oct 2020 01:52:16 +0000
From:   Peng Fan <peng.fan@....com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "ohad@...ery.com" <ohad@...ery.com>
CC:     "linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 07/13] remoteproc: Introduce function rproc_detach()

> Subject: [PATCH 07/13] remoteproc: Introduce function rproc_detach()
> 
> 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@...aro.org>
> ---
>  drivers/remoteproc/remoteproc_core.c | 65
> +++++++++++++++++++++++++++-
>  include/linux/remoteproc.h           |  1 +
>  2 files changed, 65 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c
> b/drivers/remoteproc/remoteproc_core.c
> index 7a1fc7e0620f..f3943a1e2754 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1644,7 +1644,7 @@ 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;
> @@ -1887,6 +1887,69 @@ 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_actuate()).
> + *
> + * 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 (rproc->state != RPROC_RUNNING && rproc->state !=
> RPROC_ATTACHED) {
> +		ret = -EPERM;
> +		goto out;
> +	}
> +
> +	/* if the remote proc is still needed, bail out */
> +	if (!atomic_dec_and_test(&rproc->power)) {
> +		ret = -EBUSY;
> +		goto out;
> +	}
> +
> +	ret = __rproc_detach(rproc);
> +	if (ret) {
> +		atomic_inc(&rproc->power);
> +		goto out;
> +	}
> +
> +	/* clean up all acquired resources */
> +	rproc_resource_cleanup(rproc);
> +
> +	rproc_disable_iommu(rproc);
> +
> +	/*
> +	 * Set the remote processor's table pointer to NULL.  Since mapping
> +	 * of the resource table to a virtual address is done in the platform
> +	 * driver, unmapping should also be done there.
> +	 */
> +	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
> 1a57e165da2c..6250491ee851 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -656,6 +656,7 @@ 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);
>  void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type);
> int rproc_coredump_add_segment(struct rproc *rproc, dma_addr_t da, size_t
> size);  int rproc_coredump_add_custom_segment(struct rproc *rproc,
> --


Reviewed-by: Peng Fan <peng.fan@....com>

Not relevant to your patch, just see unregister_virtio_device not set device
status when reading code, should that add device status setting in
unregister_virtio_device?