Hi Mathieu,
On 10/30/20 8:57 PM, 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@xxxxxxxxxx>
> Reviewed-by: Peng Fan <peng.fan@xxxxxxx>
> ---
> 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 62e88ff65009..6b33a83960d2 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1667,7 +1667,7 @@ 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;
> @@ -1910,6 +1910,69 @@ 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);
I'm not an IOMMU expert,so maybe this remark is not relevant...
As IOMMU manage the access of the remote device to its memory,
could this lead to a remote device crash?
Regards,
Arnaud
> +
> + /*
> + * 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 3faff9bb4fb8..6713faab6959 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,
>
