linux-kernel - Re: [PATCH v4 4/5] firmware: arm_scmi: Create debugfs files for counts

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Message-ID: <Zqo0IWvrdUUNIAGL@pluto>
Date: Wed, 31 Jul 2024 13:54:57 +0100
From: Cristian Marussi <cristian.marussi@....com>
To: Sudeep Holla <sudeep.holla@....com>
Cc: Cristian Marussi <cristian.marussi@....com>,
	Luke Parkin <luke.parkin@....com>, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, arm-scmi@...r.kernel.org
Subject: Re: [PATCH v4 4/5] firmware: arm_scmi: Create debugfs files for
 counts

On Wed, Jul 31, 2024 at 01:40:49PM +0100, Sudeep Holla wrote:
> On Wed, Jul 31, 2024 at 01:32:00PM +0100, Cristian Marussi wrote:
> > On Wed, Jul 31, 2024 at 01:11:22PM +0100, Sudeep Holla wrote:
> > > On Tue, Jul 30, 2024 at 10:33:41AM +0100, Luke Parkin wrote:
> > > > Create debugfs files for the metrics in the debug_counters array
> > > > 
> > > > Signed-off-by: Luke Parkin <luke.parkin@....com>
> > > > ---
> > > > v3->v4
> > > > Use new locations for debug array
> > > > Use counter instead of stats
> > > > v2->v3
> > > > Add extra statistics also added in v3
> > > > v1->v2
> > > > Only create stats pointer if stats are enabled
> > > > Move stats debugfs creation into a seperate helper function
> > > > ---
> > > >  drivers/firmware/arm_scmi/driver.c | 38 ++++++++++++++++++++++++++++++
> > > >  1 file changed, 38 insertions(+)
> > > > 
> > > > diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> > > > index 5acd3d324def..ec6434692d1a 100644
> > > > --- a/drivers/firmware/arm_scmi/driver.c
> > > > +++ b/drivers/firmware/arm_scmi/driver.c
> > > > @@ -2847,6 +2847,41 @@ static int scmi_device_request_notifier(struct notifier_block *nb,
> > > >  	return NOTIFY_OK;
> > > >  }
> > > >  
> > > > +static void scmi_debugfs_counters_setup(struct scmi_debug_info *dbg,
> > > > +					struct dentry *trans)
> > > > +{
> > > > +	struct dentry *counters;
> > > > +
> > > > +	counters = debugfs_create_dir("counters", trans);
> > > > +
> > > > +	debugfs_create_atomic_t("sent_ok", 0400, counters,
> > > > +				&dbg->counters[SENT_OK]);
> > > > +	debugfs_create_atomic_t("sent_fail", 0400, counters,
> > > > +				&dbg->counters[SENT_FAIL]);
> > > > +	debugfs_create_atomic_t("sent_fail_polling_unsupported", 0400, counters,
> > > > +				&dbg->counters[SENT_FAIL_POLLING_UNSUPPORTED]);
> > > > +	debugfs_create_atomic_t("sent_fail_channel_not_found", 0400, counters,
> > > > +				&dbg->counters[SENT_FAIL_CHANNEL_NOT_FOUND]);
> > > > +	debugfs_create_atomic_t("response_ok", 0400, counters,
> > > > +				&dbg->counters[RESPONSE_OK]);
> > > > +	debugfs_create_atomic_t("notif_ok", 0400, counters,
> > > > +				&dbg->counters[NOTIF_OK]);
> > > > +	debugfs_create_atomic_t("dlyd_resp_ok", 0400, counters,
> > > > +				&dbg->counters[DLYD_RESPONSE_OK]);
> > > > +	debugfs_create_atomic_t("xfers_resp_timeout", 0400, counters,
> > > > +				&dbg->counters[XFERS_RESPONSE_TIMEOUT]);
> > > > +	debugfs_create_atomic_t("response_polled_ok", 0400, counters,
> > > > +				&dbg->counters[RESPONSE_POLLED_OK]);
> > > > +	debugfs_create_atomic_t("err_msg_unexpected", 0400, counters,
> > > > +				&dbg->counters[ERR_MSG_UNEXPECTED]);
> > > > +	debugfs_create_atomic_t("err_msg_invalid", 0400, counters,
> > > > +				&dbg->counters[ERR_MSG_INVALID]);
> > > > +	debugfs_create_atomic_t("err_msg_nomem", 0400, counters,
> > > > +				&dbg->counters[ERR_MSG_NOMEM]);
> > > > +	debugfs_create_atomic_t("err_protocol", 0400, counters,
> > > > +				&dbg->counters[ERR_PROTOCOL]);
> > > 
> > > Just curious and wonder if we can keep all these read-only and have another
> > > debugfs file which is write only to just reset the counters ?
> > > 
> > > Cristian,
> > > 
> > > Thoughts ? Or am I missing somthing ?
> > 
> > Do you mean creating a bunch of additional reset_sent_ok
> > reset_<your_counters> that are just WO and used to reset each single
> > counter ?
> 
> No, not at all. Sorry if my response meant that.
> 
> > (...I suppose because a global WO reset-all is already there...)
> >
> 
> Indeed, I hadn't seen it carefully. Do we really need per counter reset ?
> For me one global reset all with all files read-only should suffice.
> Let me know if and why you think otherwise.

Well we don't need strictly anything since it is a debug/devel feat, it
just seemed handy to have a way to just reset one of the counters you are
actively working on, if you think about a testing or live devel
scenario...but it is not really needed and I have no strong opinion
about this...it was just a nice to have I asked Luke to add last minute...

...patch 5 indeed already adds also a global WO reset, beside switching all
the above counters to RW...it is just a matter to drop those RO->RW perms
changes in patch 5.

Thanks,
Cristian