linux-kernel - Re: [PATCH 0/2] PATCH: firmware: ti

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Message-ID: <CADL8D3aR_ecr4q54cX7yfr_aDPA7NhXmLhkiHjUY9MjNZeg78Q@mail.gmail.com>
Date: Fri, 22 Aug 2025 12:05:08 -0400
From: Jon Cormier <jcormier@...ticallink.com>
To: Andrew Davis <afd@...com>
Cc: Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>, 
	Santosh Shilimkar <ssantosh@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, 
	Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, 
	Vignesh Raghavendra <vigneshr@...com>, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] PATCH: firmware: ti_sci: Add trace events to TI SCI

On Wed, Aug 20, 2025 at 4:04 PM Andrew Davis <afd@...com> wrote:
>
> On 8/20/25 1:10 PM, Jonathan Cormier wrote:
> > Add trace events to help debug and measure the speed of the
> > communication channel.
> >
> > Add parsing of the messages types but I am not sure how to parse the
> > flags, since the REQ and RESP flags conflict. Left as seperate commit to
>
> The REQ and RESP flags should be handled by different TRACE_EVENTs. Right
> now you only dump the content of the response messages (the ones in
> rx_callback), also tracing what is sent is just as important, so you
> might want to add slightly different ti_sci_msg_dump EVENT for the
> sending side which uses the different REQ flag parser.


Does it make sense to have seperate trace events, one that only decode
the hdrs and ones that also include the buffers?

I'm bothered by the code duplication, but am trying to convince myself
it doesn't matter.

Currently, with the above updates, if you enabled all the traces,
you'd see something like:

[15.579036] ti_sci_xfer_begin: type=SET_DEVICE_STATE host=0C seq=00
flags=00000402 status=0
[15.xxxxxxx] ti_sci_tx_msg_dump: type=SET_DEVICE_STATE host=0C seq=00
flags=00000402 data=<data>
[15.587595] ti_sci_rx_callback: type=SET_DEVICE_STATE host=0C seq=00
flags=00000002 status=0
[15.xxxxxxx] ti_sci_rx_msg_dump: type=SET_DEVICE_STATE host=0C seq=00
flags=00000002 data=<data>
[15.606135] ti_sci_xfer_end: type=SET_DEVICE_STATE host=0C seq=00
flags=00000002 status=0

Presumably if you were worried about timing, you'd disable the
msg_dumps, avoiding the extra memcpy's.  And if you only cared about
the data being sent, you'd only enable the msg_dumps.  Does this make
sense / is it worth the extra trace calls?

Or removing the buffer decoding in the msg_dumps, removes the duplication:

[15.579036] ti_sci_xfer_begin: type=SET_DEVICE_STATE host=0C seq=00
flags=00000402 status=0
[15.xxxxxxx] ti_sci_msg_dump: data=<data>
[15.587595] ti_sci_rx_callback: type=SET_DEVICE_STATE host=0C seq=00
flags=00000002 status=0
[15.xxxxxxx] ti_sci_msg_dump: data=<data>
[15.606135] ti_sci_xfer_end: type=SET_DEVICE_STATE host=0C seq=00
flags=00000002 status=0

Or do condense the trace calls so they all have the data into something like:

[15.579036] ti_sci_xfer_begin: type=SET_DEVICE_STATE host=0C seq=00
flags=00000402 status=0  data=<data>
[15.587595] ti_sci_rx_callback: type=SET_DEVICE_STATE host=0C seq=00
flags=00000002 status=0 data=<data>
[15.606135] ti_sci_xfer_end: type=SET_DEVICE_STATE host=0C seq=00
flags=00000002 status=0

Simplifying the code in the trace header.
>
>
> Andrew
>
> > make it easier to drop or make changes depending on comments.  The two
> > commits should squash easily.
> >
> > Nishanth Menon and Vignesh Raghavendra requested I send this patch
> > upstream.
> >
> > Signed-off-by: Jonathan Cormier <jcormier@...ticallink.com>
> > ---
> > Jonathan Cormier (2):
> >        firmware: ti_sci: Add trace events
> >        firmware: ti_sci: trace: Decode message types
> >
> >   MAINTAINERS                     |   1 +
> >   drivers/firmware/Makefile       |   3 +
> >   drivers/firmware/ti_sci.c       |  11 +++
> >   drivers/firmware/ti_sci_trace.h | 146 ++++++++++++++++++++++++++++++++++++++++
> >   4 files changed, 161 insertions(+)
> > ---
> > base-commit: d7b8f8e20813f0179d8ef519541a3527e7661d3a
> > change-id: 20250709-linux_master_ti_sci_trace-91fd2af65dca
> >
> > Best regards,
>


-- 
Jonathan Cormier
Senior Software Engineer

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