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Date:   Thu, 5 May 2022 19:38:24 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Frank Wunderlich <frank-w@public-files.de>
Cc:     Viresh Kumar <viresh.kumar@linaro.org>,
        Frank Wunderlich <linux@fw-web.de>, linux-pm@vger.kernel.org,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
        Stephen Boyd <sboyd@kernel.org>, linux-kernel@vger.kernel.org
Subject: Re: Aw: Re: [RFC v1] opp: add config option for debug
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On Thu, May 05, 2022 at 05:54:18PM +0200, Frank Wunderlich wrote:
> Hi,
> 
> > Gesendet: Donnerstag, 05. Mai 2022 um 07:58 Uhr
> > Von: "Viresh Kumar" <viresh.kumar@linaro.org>
> > An: "Frank Wunderlich" <linux@fw-web.de>
> > Cc: linux-pm@vger.kernel.org, "Frank Wunderlich" <frank-w@public-files.de>, "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>, "Rafael J. Wysocki" <rafael@kernel.org>, "Viresh Kumar" <vireshk@kernel.org>, "Nishanth Menon" <nm@ti.com>, "Stephen Boyd" <sboyd@kernel.org>, linux-kernel@vger.kernel.org
> > Betreff: Re: [RFC v1] opp: add config option for debug
> >
> > On 04-05-22, 19:48, Frank Wunderlich wrote:
> > > From: Frank Wunderlich <frank-w@public-files.de>
> > >
> > > Currently OPP debug is enabled by DEBUG_DRIVER option. This is generic
> > > driver debug and opp floods serial console. This is annoying if opp is
> > > not needed so give it an additional config-key.
> > >
> > > Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
> > > ---
> > >  drivers/base/Kconfig | 1 +
> > >  drivers/opp/Kconfig  | 7 +++++++
> > >  drivers/opp/Makefile | 2 +-
> > >  3 files changed, 9 insertions(+), 1 deletion(-)
> >
> > Isn't something like Dynamic Debug helpful here ?
> 
> you mean something like this:
> 
> https://www.kernel.org/doc/html/v5.17/admin-guide/dynamic-debug-howto.html#debug-messages-during-boot-process
> 
> so enabling debug only with cmdline-param...
> 
> have you a simple example how to implement it? have not done anything with dynamic-debug yet...seems mighty but not trivial to implement.
> 
> currently dev_dbg() is used for the messages that i try to disable...but show others from driver_debug at debug level.
> 
> What needs to be changed to filter it via DYNAMIC_DEBUG?
> 
> found this, but i'm not sure if i interpret it the right way...
> 
> https://elixir.bootlin.com/linux/v5.18-rc5/source/drivers/acpi/utils.c#L495
> defines __acpi_handle_debug
> called via acpi_handle_debug macro
> https://elixir.bootlin.com/linux/v5.18-rc5/source/include/linux/acpi.h#L1136
> 
> so basicly convert dev_dbg to __dynamic_pr_debug

Ick, no, just stick with all dev_dbg() calls and do not add any Makefile
changes and all should be fine.  And drop the Kconfig option, should not
be needed for a subsystem/driver at all.

thanks,

greg k-h