linux-kernel - Re: [PATCH v5 5/5] misc serdev: w2sg0004: add debugging code and Kconfig

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Date:   Fri, 22 Dec 2017 15:58:13 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Johan Hovold <johan@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Benoît Cousson <bcousson@...libre.com>,
        Tony Lindgren <tony@...mide.com>,
        Russell King <linux@...linux.org.uk>,
        Arnd Bergmann <arnd@...db.de>,
        Kevin Hilman <khilman@...libre.com>,
        Andreas Färber <afaerber@...e.de>,
        Thierry Reding <treding@...dia.com>,
        Jonathan Cameron <jic23@...nel.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org, letux-kernel@...nphoenux.org,
        kernel@...a-handheld.com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5 5/5] misc serdev: w2sg0004: add debugging code and
 Kconfig

On Fri, Dec 22, 2017 at 03:41:24PM +0100, H. Nikolaus Schaller wrote:
> 
> > Am 22.12.2017 um 13:51 schrieb Johan Hovold <johan@...nel.org>:
> > 
> > On Fri, Dec 01, 2017 at 08:49:38AM +0100, H. Nikolaus Schaller wrote:
> >> This allows to set CONFIG_W2SG0004_DEBUG which will
> >> make the driver report more activities and it will turn on the
> >> GPS module during boot while the driver assumes that it
> >> is off. This can be used to debug the correct functioning of
> >> the hardware. Therefore we add it as an option to the driver
> >> because we think it is of general use (and a little tricky to
> >> add by system testers).
> >> 
> >> Normally it should be off.
> >> 
> >> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
> >> ---
> >> drivers/misc/Kconfig    |  8 ++++++++
> >> drivers/misc/w2sg0004.c | 37 +++++++++++++++++++++++++++++++++++++
> >> 2 files changed, 45 insertions(+)
> > 
> > I'd say say this does not belong in the kernel at all.
> 
> There are other examples of such DEBUG options for drivers.
> E.g. CONFIG_LIBERTAS_DEBUG.

And that is wrong and should be removed.

> It helps the hardware developer to test things and should of course
> be disabled in a production kernel.

dev_dbg() should be used instead.  And you can always hard-code #define DEBUG
at the top of your file when doing bringup.

thanks,

greg k-h