From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-x243.google.com (mail-it0-x243.google.com [IPv6:2607:f8b0:4001:c0b::243]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3zRt8Q3ZlszDqF9 for ; Thu, 25 Jan 2018 17:55:18 +1100 (AEDT) Received: by mail-it0-x243.google.com with SMTP id e1so8184986ita.0 for ; Wed, 24 Jan 2018 22:55:17 -0800 (PST) Subject: Re: [RFC PATCH v2 0/1] of: easier debugging for node life cycle issues To: Wolfram Sang , devicetree@vger.kernel.org, Steven Rostedt Cc: Tyrel Datwyler , Geert Uytterhoeven , linux-renesas-soc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Rob Herring , linux-kernel@vger.kernel.org References: <20180121143117.19805-1-wsa+renesas@sang-engineering.com> From: Frank Rowand Message-ID: <00fc90ee-de26-f819-9c81-27d06918564d@gmail.com> Date: Wed, 24 Jan 2018 22:55:13 -0800 MIME-Version: 1.0 In-Reply-To: <20180121143117.19805-1-wsa+renesas@sang-engineering.com> Content-Type: text/plain; charset=utf-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Steve, On 01/21/18 06:31, Wolfram Sang wrote: > I got a bug report for a DT node refcounting problem in the I2C subsystem. This > patch was a huge help in validating the bug report and the proposed solution. > So, I thought I bring it to attention again. Thanks Tyrel, for the initial > work! > > Note that I did not test the dynamic updates, only of_node_{get|put} so far. I > read that Tyrel checked dynamic updates extensively with this patch. And since > DT overlays are also used within our Renesas dev team, this will help there, as > well. > > Tested on a Renesas Salvator-XS board (R-Car H3). > > Changes since RFC v1: > * rebased to v4.15-rc8 > * fixed commit abbrev and one of the sysfs paths in commit desc > * removed trailing space and fixed pointer declaration in code > > I consider all the remaining checkpatch issues irrelevant for this patch. > > So what about applying it? > > Kind regards, > > Wolfram > > > Tyrel Datwyler (1): > of: introduce event tracepoints for dynamic device_node lifecyle > > drivers/of/dynamic.c | 32 ++++++---------- > include/trace/events/of.h | 93 +++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 105 insertions(+), 20 deletions(-) > create mode 100644 include/trace/events/of.h > Off the top of your head, can you tell me know early in the boot process a trace_event can be called and successfully provide the data to someone trying to debug early boot issues? Also, way back when version 1 of this patch was being discussed, a question about stacktrace triggers: >>> # echo stacktrace > /sys/kernel/debug/tracing/trace_options >>> # cat trace | grep -A6 "/pci@800000020000018" >> >> Just to let you know that there is now stacktrace event triggers, where >> you don't need to stacktrace all events, you can pick and choose. And >> even filter the stack trace on specific fields of the event. > > This is great, and I did figure that out this afternoon. One thing I was > still trying to determine though was whether its possible to set these > triggers at boot? As far as I could tell I'm still limited to > "trace_options=stacktrace" as a kernel boot parameter to get the stack > for event tracepoints. No not yet. But I'll add that to the todo list. Thanks, -- Steve Is this still on your todo list, or is it now available? Thanks, Frank