linux-kernel - RE: [PATCH 0/4] firmware: arm_scmi: Add xfer inflight debug and trace

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Message-ID:
 <PAWPR08MB9966E79130C52CA8460AC4B7897CA@PAWPR08MB9966.eurprd08.prod.outlook.com>
Date: Fri, 20 Jun 2025 09:27:52 +0000
From: Philip Radford <Philip.Radford@....com>
To: Peng Fan <peng.fan@....nxp.com>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "arm-scmi@...r.kernel.org"
	<arm-scmi@...r.kernel.org>, Sudeep Holla <Sudeep.Holla@....com>, Cristian
 Marussi <Cristian.Marussi@....com>, Luke Parkin <Luke.Parkin@....com>
Subject: RE: [PATCH 0/4] firmware: arm_scmi: Add xfer inflight debug and trace



> -----Original Message-----
> From: Peng Fan <peng.fan@....nxp.com>
> Sent: Friday, June 20, 2025 9:47 AM
> To: Philip Radford <Philip.Radford@....com>

Hi,
Thanks for the review.

> Cc: linux-kernel@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; arm-
> scmi@...r.kernel.org; Sudeep Holla <Sudeep.Holla@....com>; Cristian
> Marussi <Cristian.Marussi@....com>; Luke Parkin <Luke.Parkin@....com>
> Subject: Re: [PATCH 0/4] firmware: arm_scmi: Add xfer inflight debug and
> trace
> 
> On Thu, Jun 19, 2025 at 12:20:00PM +0000, Philip Radford wrote:
> >Hi all,
> >
> >This series adds a new counter to the Arm SCMI firmware driver to track
> >the number of in-flight message transfers during debug and trace. This
> >will be useful for examining behaviour under a large load with regards
> >to concurrent messages being sent and received. As the counter only gives
> >a live value, printing the value in trace allows logging of the in-flight
> >xfers.
> 
> Just a general question, is this counter count in flight messages
> for a scmi instance or it is per transport? I ask because
> one scmi instance could have multiple mailboxes. If counting based
> on scmi instance, it may not be that accurate.
> 
> Thanks,
> Peng
> 

Yes, you are correct that the counter is per instance, as are the other counters.
This would mean that if you have multiple channels you would see the total
number of inflight xfers across all channels, limited to that instance.
If the inflight counter is non-zero and something is wrong, it would not be
apparent which channel had an issue, however this is the same for the other
counters.

I feel like this series is a helpful addition to the current counters, but what you
have pointed out is something that could be reworked in a future series?

Regards,
Phil