Re: [PATCH v2 2/4] firmware: arm_scmi: Add support for tracking statistics

[Cristian Marussi <cristian.marussi@arm.com>]

On Wed, Jul 03, 2024 at 03:37:36PM +0100, Luke Parkin wrote:
> Add a new config option for statistic tracking in SCMI subsystem
> Add a struct for tracking statistics
> Add scmi_log_stats op/no-op function for incrementing statistics
> 

Hi Luke,

good that you keep a summary of viersion changes in the series you
are posting to aid in review....but...

> Signed-off-by: Luke Parkin <luke.parkin@arm.com>

...you need a 

---

...separator here before the summary

> v1->v2
> Config option now depends on DEBUG_FS
> Add scmi_log_stats rather than if(IS_ENABLED)
> Move location of scmi_debug_stats in the scmi_info struct

...if not this sumamry info will be kept in the final merged commit
message, which is not what we want...this is only for the sake of
reviews...

> ---
>  drivers/firmware/arm_scmi/Kconfig  | 11 +++++++++++
>  drivers/firmware/arm_scmi/common.h |  9 +++++++++
>  drivers/firmware/arm_scmi/driver.c | 18 ++++++++++++++++++
>  3 files changed, 38 insertions(+)
> 
> diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig
> index aa5842be19b2..45e8e7df927e 100644
> --- a/drivers/firmware/arm_scmi/Kconfig
> +++ b/drivers/firmware/arm_scmi/Kconfig
> @@ -55,6 +55,17 @@ config ARM_SCMI_RAW_MODE_SUPPORT_COEX
>  	  operate normally, thing which could make an SCMI test suite using the
>  	  SCMI Raw mode support unreliable. If unsure, say N.
>  
> +config ARM_SCMI_DEBUG_STATISTICS
> +	bool "Enable SCMI Raw mode statistic tracking"
> +	select ARM_SCMI_NEED_DEBUGFS
> +	depends on DEBUG_FS
> +	help
> +	  Enables statistic tracking for the SCMI subsystem.
> +
> +	  Enable this option to create a new debugfs directory which contains
> +	  several useful statistics on various SCMI features. This can be useful
> +	  for debugging and SCMI monitoring. If unsure, say N.
> +
>  config ARM_SCMI_HAVE_TRANSPORT
>  	bool
>  	help
> diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
> index b5ac25dbc1ca..1f50c4a209d7 100644
> --- a/drivers/firmware/arm_scmi/common.h
> +++ b/drivers/firmware/arm_scmi/common.h
> @@ -301,6 +301,15 @@ extern const struct scmi_desc scmi_optee_desc;
>  
>  void scmi_rx_callback(struct scmi_chan_info *cinfo, u32 msg_hdr, void *priv);
>  
> +#ifdef CONFIG_ARM_SCMI_DEBUG_STATISTICS
> +static inline void scmi_log_stats(atomic_t *atm)
> +{
> +	atomic_inc(atm);
> +}
> +#else
> +static inline void scmi_log_stats(atomic_t *atm) {}
> +#endif
> +
>  enum scmi_bad_msg {
>  	MSG_UNEXPECTED = -1,
>  	MSG_INVALID = -2,
> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index 56a93d20bf23..df3eb17cf439 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -125,6 +125,22 @@ struct scmi_debug_info {
>  	bool is_atomic;
>  };
>  
> +/**
> + * struct scmi_debug_stats - Debug statistics
> + * @sent_ok: Count of successful sends
> + * @sent_fail: Count of failed sends
> + * @response_ok: Count of successful responses
> + * @dlyd_response_ok: Count of successful delayed responses
> + * @xfers_response_timeout: Count of xfer response timeouts
> + */
> +struct scmi_debug_stats {
> +	atomic_t sent_ok;
> +	atomic_t sent_fail;
> +	atomic_t response_ok;
> +	atomic_t dlyd_response_ok;
> +	atomic_t xfers_response_timeout;
> +};
> +
>  /**
>   * struct scmi_info - Structure representing a SCMI instance
>   *
> @@ -161,6 +177,7 @@ struct scmi_debug_info {
>   *		bus
>   * @devreq_mtx: A mutex to serialize device creation for this SCMI instance
>   * @dbg: A pointer to debugfs related data (if any)
> + * @stats: Contains several atomic_t's for tracking various statistics
>   * @raw: An opaque reference handle used by SCMI Raw mode.
>   */
>  struct scmi_info {
> @@ -187,6 +204,7 @@ struct scmi_info {
>  	/* Serialize device creation process for this instance */
>  	struct mutex devreq_mtx;
>  	struct scmi_debug_info *dbg;
> +	struct scmi_debug_stats stats;
>  	void *raw;
>  };

Once the above nitpicks are fixed, I think this is good enough for our
purposes for now; optionally we could quickly move to a macro-based machinery
to avoid carrying the stats field in full even when STATS=n if someone
prefers that way... 

.... but...I will ask you anyway to add a few more stats in the next patch
by splitting a few of the existing ones...

Thanks,
Cristian