Re: [PATCH] coresight: etm4x: Add support to disable trace unit power up

[Sai Prakash Ranjan]

Hi Mathieu,

On 2020-05-15 21:21, Mathieu Poirier wrote:
> On Fri, May 15, 2020 at 08:37:13PM +0530, Sai Prakash Ranjan wrote:
> > Hi Mathieu,
> >
> > On 2020-05-15 20:22, Mathieu Poirier wrote:
> > > On Thu, 14 May 2020 at 12:39, Sai Prakash Ranjan
> > > <saiprakash.ranjan@xxxxxxxxxxxxxx> wrote:
> > > >
> > > > Hi Mathieu,
> > > >
> > > > On 2020-05-14 23:30, Mathieu Poirier wrote:
> > > > > Good morning Sai,
> > > > >
> > > > > On Thu, May 14, 2020 at 04:29:15PM +0530, Sai Prakash Ranjan wrote:
> > > > >> From: Tingwei Zhang <tingwei@xxxxxxxxxxxxxx>
> > > > >>
> > > > >> On some Qualcomm Technologies Inc. SoCs like SC7180, there
> > > > >> exists a hardware errata where the APSS (Application Processor
> > > > >> SubSystem)/CPU watchdog counter is stopped when ETM register
> > > > >> TRCPDCR.PU=1.
> > > > >
> > > > > Fun stuff...
> > > > >
> > > >
> > > > Yes :)
> > > >
> > > > >> Since the ETMs share the same power domain as
> > > > >> that of respective CPU cores, they are powered on when the
> > > > >> CPU core is powered on. So we can disable powering up of the
> > > > >> trace unit after checking for this errata via new property
> > > > >> called "qcom,tupwr-disable".
> > > > >>
> > > > >> Signed-off-by: Tingwei Zhang <tingwei@xxxxxxxxxxxxxx>
> > > > >> Co-developed-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> > > > >> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> > > > >
> > > > > Co-developed-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> > > > > Signed-off-by: Tingwei Zhang <tingwei@xxxxxxxxxxxxxx>
> > > > >
> > > >
> > > > Tingwei is the author, so if I understand correctly, his signed-off-by
> > > > should appear first, am I wrong?
> > >
> > > It's a gray area and depends on who's code is more prevalent in the
> > > patch.  If Tingwei wrote the most of the code then his name is in the
> > > "from:" section, yours as co-developer and he signs off on it (as I
> > > suggested).  If you did most of the work then it is the opposite.
> > > Adding a Co-developed and a signed-off with the same name doesn't make
> > > sense.
> > >
> >
> > I did check the documentation for submitting patches:
> > Documentation/process/submitting-patches.rst. And it clearly states
> > that "Co-developed-by must be followed by Signed-off by the co-author
> > and the last Signed-off-by: must always be that of the developer
> > submitting the patch".
> >
> > Quoting below from the doc:
> >
> > Co-developed-by: <snip> ...Since
> > Co-developed-by: denotes authorship, every Co-developed-by: must be
> > immediately
> > followed by a Signed-off-by: of the associated co-author.  Standard 
> > sign-off
> > procedure applies, i.e. the ordering of Signed-off-by: tags should 
> > reflect
> > the
> > chronological history of the patch insofar as possible, regardless of
> > whether
> > the author is attributed via From: or Co-developed-by:.  Notably, the 
> > last
> > Signed-off-by: must always be that of the developer submitting the 
> > patch.
>
> Ah yes, glad to see that got clarified.  You can ignore my 
> recommendation on
> that snippet.
>
> > > >
> > > > >> ---
> > > > >>  .../devicetree/bindings/arm/coresight.txt     |  6 ++++
> > > > >>  drivers/hwtracing/coresight/coresight-etm4x.c | 29
> > > > >> ++++++++++++-------
> > > > >
> > > > > Please split in two patches.
> > > > >
> > > >
> > > > Sure, I will split the dt-binding into separate patch, checkpatch did
> > > > warn.
> > >
> > > And you still sent me the patch...  I usually run checkpatch before
> > > all the submissions I review and flatly ignore patches that return
> > > errors.  You got lucky...
> > >
> >
> > I did not mean to ignore it or else I wouldn't have run checkpatch 
> > itself.
> > I checked other cases like "arm,scatter-gather" where the binding and 
> > the
> > driver change was in a single patch, hence I thought it's not a very 
> > strict
> > rule.
>
> The patch has another warning for a line over 80 characters, that 
> should have
> been fixed before sending.  Putting DT changes in a separate patch is 
> always
> better for the DT people.  They review tons of patches and making their 
> life
> easier is always a good thing.

Ok, I will fix this and resend. I did not want to change it in case if 
it affects
readability since most maintainers prefer to ignore this 80 characters 
warning if
it affects readability. I will keep this in mind for future patches as 
well.

Thanks,
Sai
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