Re: [PATCH v2] [media] v4l: omap4iss: Add DEBUG compiler flag

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Mar 06, 2014 at 01:48:29AM +0100, Laurent Pinchart wrote:
> Hi Joe,
> 
> On Wednesday 05 March 2014 16:28:03 Joe Perches wrote:
> > On Thu, 2014-03-06 at 00:50 +0100, Laurent Pinchart wrote:
> > > Please note that -DDEBUG is equivalent to '#define DEBUG', not to '#define
> > > CONFIG_DEBUG'. 'DEBUG' needs to be defined for dev_dbg() to have any
> > > effect.
> >
> > Not quite.  If CONFIG_DYNAMIC_DEBUG is set, these
> > dev_dbg statements are compiled in but not by default
> > set to emit output.  Output can be enabled by using
> > dynamic_debug controls like:
> > 
> > # echo -n 'file omap4iss/* +p' > <debugfs>/dynamic_debug/control
> > 
> > See Documentation/dynamic-debug-howto.txt for more details.
> 
> Thank you for the additional information.
> 
> Would you recommend to drop driver-specific Kconfig options related to 
> debugging and use CONFIG_DYNAMIC_DEBUG instead ?

Yes, please do that, no one wants to rebuild drivers and subsystems with
different options just for debugging.

thanks,

greg k-h