Re: [PATCH v15 24/35] firmware: arm_scmi: Add common per-protocol debugfs support

[Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>]

On Mon,  9 Nov 2026 09:12:10 +0000
Cristian Marussi <cristian.marussi@arm.com> wrote:

> Allow interested SCMI protocols to register their own specific debugfs
> entries under a common per-instance and per-protocol subtree rooted
> at /sys/kernel/debug/scmi/<N>/protocols/<PROTO_ID>/
> 
> Expose a helper to enable protocol initialization code to get access to
> such per-protocol/per-instance dentries in order to be able to install
> their own dedicated debugfs entries.
> 
> Per-protocol debugfs support is configurable and default off.
> 
> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
> ---
> v14 --> v15
>  - fix debugfs_remove_recursive call-site...was too early
> v8 --> v9
>  - avoid NULL deref on DBG cleanup path
> v5 --> v6
>  - bail out of dentry_get helper when SCMI debug susbsytem failed to init
>  - remove stale SCMI protocol operations
>  - add a preoper clean up of debugfs when protocol init fails
> ---
>  drivers/firmware/arm_scmi/Kconfig     | 14 +++++++++
>  drivers/firmware/arm_scmi/common.h    |  2 ++
>  drivers/firmware/arm_scmi/driver.c    | 42 +++++++++++++++++++++++++--
>  drivers/firmware/arm_scmi/protocols.h |  6 ++++
>  include/linux/scmi_protocol.h         |  1 -
>  5 files changed, 62 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig
> index 783c24a20e29..f506c4d1d96a 100644
> --- a/drivers/firmware/arm_scmi/Kconfig
> +++ b/drivers/firmware/arm_scmi/Kconfig
> @@ -69,6 +69,20 @@ config ARM_SCMI_DEBUG_COUNTERS
>  	  such useful debug counters. This can be helpful for debugging and
>  	  SCMI monitoring.
>  
> +config ARM_SCMI_DEBUG_PROTOCOLS
> +	bool "Enable SCMI protocols debug"
> +	select ARM_SCMI_NEED_DEBUGFS
> +	depends on DEBUG_FS
> +	default n

default of default is n, so no need.  By all means add some text
to discourage distros from enabling it.

> +	help
> +	  Enables per-protocol specific debug features, where available.
> +	  When provided, such per-protocol debugfs entries are grouped
> +	  inside a common a subtree named by the protocol number and rooted
> +	  under a per-instance 'protocols' directory.
> +
> +	  Such per-protocol entries subtree structure is freely defined
> +	  within the related protocol code.
> +

> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index c1f503c6e72c..8a4664165a64 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c


> diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
> index 585eb3a4684e..ed3eaa1482a3 100644
> --- a/include/linux/scmi_protocol.h
> +++ b/include/linux/scmi_protocol.h
> @@ -1164,7 +1164,6 @@ struct scmi_handle {
>  	void (*devm_protocol_put)(struct scmi_device *sdev, u8 proto);
>  	bool (*is_transport_atomic)(const struct scmi_handle *handle,
>  				    unsigned int *atomic_threshold);
> -
Unrelated.  Scrub for this stuff before sending new versions. Saves time
all round for a minute or two sanity checking.

>  	const struct scmi_notify_ops *notify_ops;
>  };
>