Re: [PATCH 6/6] remoteproc: qcom: Add notification types to SSR

Mathieu Poirier
2020-02-27T21:59:47Z

On Wed, Feb 19, 2020 at 06:57:45PM -0800, Siddharth Gupta wrote:
> The SSR subdevice only adds callback for the unprepare event. Add callbacks
> for unprepare, start and prepare events. The client driver for a particular
> remoteproc might be interested in knowing the status of the remoteproc
> while undergoing SSR, not just when the remoteproc has finished shutting
> down.
>
> Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
> ---
> drivers/remoteproc/qcom_common.c | 39 +++++++++++++++++++++++++++++++++++----
> include/linux/remoteproc.h | 15 +++++++++++++++
> 2 files changed, 50 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/remoteproc/qcom_common.c b/drivers/remoteproc/qcom_common.c
> index 6714f27..6f04a5b 100644
> --- a/drivers/remoteproc/qcom_common.c
> +++ b/drivers/remoteproc/qcom_common.c
> @@ -183,9 +183,9 @@ EXPORT_SYMBOL_GPL(qcom_remove_smd_subdev);
> *
> * Returns pointer to srcu notifier head on success, ERR_PTR on failure.
> *
> - * This registers the @notify function as handler for restart notifications. As
> - * remote processors are stopped this function will be called, with the rproc
> - * pointer passed as a parameter.
> + * This registers the @notify function as handler for powerup/shutdown
> + * notifications. This function will be invoked inside the callbacks registered
> + * for the ssr subdevice, with the rproc pointer passed as a parameter.
> */
> void *qcom_register_ssr_notifier(struct rproc *rproc, struct notifier_block *nb)
> {
> @@ -227,11 +227,39 @@ int qcom_unregister_ssr_notifier(void *notify, struct notifier_block *nb)
> }
> EXPORT_SYMBOL_GPL(qcom_unregister_ssr_notifier);
>
> +static int ssr_notify_prepare(struct rproc_subdev *subdev)
> +{
> + struct qcom_rproc_ssr *ssr = to_ssr_subdev(subdev);
> +
> + srcu_notifier_call_chain(ssr->rproc_notif_list,
> + RPROC_BEFORE_POWERUP, (void *)ssr->name);
> + return 0;
> +}
> +
> +static int ssr_notify_start(struct rproc_subdev *subdev)
> +{
> + struct qcom_rproc_ssr *ssr = to_ssr_subdev(subdev);
> +
> + srcu_notifier_call_chain(ssr->rproc_notif_list,
> + RPROC_AFTER_POWERUP, (void *)ssr->name);
> + return 0;
> +}
> +
> +static void ssr_notify_stop(struct rproc_subdev *subdev, bool crashed)
> +{
> + struct qcom_rproc_ssr *ssr = to_ssr_subdev(subdev);
> +
> + srcu_notifier_call_chain(ssr->rproc_notif_list,
> + RPROC_BEFORE_SHUTDOWN, (void *)ssr->name);
> +}
> +
> +
> static void ssr_notify_unprepare(struct rproc_subdev *subdev)
> {
> struct qcom_rproc_ssr *ssr = to_ssr_subdev(subdev);
>
> - srcu_notifier_call_chain(ssr->rproc_notif_list, 0, (void *)ssr->name);
> + srcu_notifier_call_chain(ssr->rproc_notif_list,
> + RPROC_AFTER_SHUTDOWN, (void *)ssr->name);
> }
>
> /**
> @@ -248,6 +276,9 @@ void qcom_add_ssr_subdev(struct rproc *rproc, struct qcom_rproc_ssr *ssr,
> {
> ssr->name = ssr_name;
> ssr->subdev.name = kstrdup("ssr_notifs", GFP_KERNEL);
> + ssr->subdev.prepare = ssr_notify_prepare;
> + ssr->subdev.start = ssr_notify_start;
> + ssr->subdev.stop = ssr_notify_stop;

Now that I have a better understanding of what this patchset is doing, I realise
my comments in patch 04 won't work. To differentiate the subdevs of an rproc I
suggest to wrap them in a generic structure with a type and an enum. That way
you can differenciate between subdevices without having to add to the core.

That being said, I don't understand what patches 5 and 6 are doing...
Registering with the global ssr_notifiers allowed to gracefully shutdown all the
MCUs in the system when one of them would go down. But now that we are using
the notifier on a per MCU, I really don't see why each subdev couldn't implement
the right prepare/start/stop functions.

Am I missing something here?

> ssr->subdev.unprepare = ssr_notify_unprepare;
> ssr->rproc_notif_list = kzalloc(sizeof(struct srcu_notifier_head),
> GFP_KERNEL);
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index e2f60cc..4be4478 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -449,6 +449,21 @@ struct rproc_dump_segment {
> };
>
> /**
> + * enum rproc_notif_type - Different stages of remoteproc notifications
> + * @RPROC_BEFORE_SHUTDOWN: unprepare stage of remoteproc
> + * @RPROC_AFTER_SHUTDOWN: stop stage of remoteproc
> + * @RPROC_BEFORE_POWERUP: prepare stage of remoteproc
> + * @RPROC_AFTER_POWERUP: start stage of remoteproc
> + */
> +enum rproc_notif_type {
> + RPROC_BEFORE_SHUTDOWN,
> + RPROC_AFTER_SHUTDOWN,
> + RPROC_BEFORE_POWERUP,
> + RPROC_AFTER_POWERUP,
> + RPROC_MAX
> +};
> +
> +/**
> * struct rproc - represents a physical remote processor device
> * @node: list node of this rproc object
> * @domain: iommu domain
> --
> Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
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