Hi Mauro, On Friday 21 August 2015 07:19:21 Mauro Carvalho Chehab wrote: > Em Fri, 21 Aug 2015 04:32:51 +0300 Laurent Pinchart escreveu: > > On Wednesday 19 August 2015 08:01:54 Mauro Carvalho Chehab wrote: > > > It helps to check if the media controller is doing the > > > right thing with the object creation and removal. > > > > > > No extra code/data will be produced if DEBUG or > > > CONFIG_DYNAMIC_DEBUG is not enabled. > > > > CONFIG_DYNAMIC_DEBUG is often enabled. > > True, but once a driver/core is properly debugged, images without DEBUG > could be used in production, if the amount of memory constraints are > too tight. > > > You're more or less adding function call tracing in this patch, isn't that > > something that ftrace is supposed to do ? > > Ftrace is a great infrastructure and helps a lot when we need to > identify bottlenecks and other performance related stuff, but it > doesn't replace debug functions. > > There are some fundamental differences on what you could do with ftrace > and what you can't. > > At least on this stage, what I need is something that will provide > output via serial console when the driver gets loaded, and that provides > a synchronous output with the other Kernel messages. > > This is the only way to debug certain OOPSes that are happening during > the development of the patches. > > This is something you cannot do with ftrace, but dynamic DEBUG works > like a charm. I understand the need for debug messages during development of a patch series, but I don't think this level of debugging belongs to mainline. Debug messages for function call tracing, even more in patch 6/8 and 7/8, is frowned upon in the kernel. Or maybe I got it wrong and patches 6/8 and 7/8 are only for development and you don't plan to get them in mainline ? -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
