Re: [alsa-devel] [PATCH v4 08/15] soundwire: add initial definitions for sdw_master_device

[Pierre-Louis Bossart]

On 12/14/19 2:27 AM, Greg KH wrote:
> On Fri, Dec 13, 2019 at 05:25:23PM -0600, Pierre-Louis Bossart wrote:
> > > No, I mean the new MODULE_NAMESPACE() support that is in the kernel.
> > > I'll move the greybus code to use it too, but when you are adding new
> > > apis, it just makes sense to use it then as well.
> >
> > Greg, would the patch below be what you had in mind?
> > Thanks
> > -Pierre
> >
> >
> > diff --git a/drivers/soundwire/Makefile b/drivers/soundwire/Makefile
> > index 76a5c52b12b4..5bad8422887e 100644
> > --- a/drivers/soundwire/Makefile
> > +++ b/drivers/soundwire/Makefile
> > @@ -7,9 +7,11 @@ ccflags-y += -DDEBUG
> >   #Bus Objs
> >   soundwire-bus-objs := bus_type.o bus.o master.o slave.o mipi_disco.o
> > stream.o
> >   obj-$(CONFIG_SOUNDWIRE) += soundwire-bus.o
> > +ccflags-$(CONFIG_SOUNDWIRE) += -DDEFAULT_SYMBOL_NAMESPACE=SDW_CORE
> >
> >   soundwire-generic-allocation-objs := generic_bandwidth_allocation.o
> >   obj-$(CONFIG_SOUNDWIRE_GENERIC_ALLOCATION) +=
> > soundwire-generic-allocation.o
> > +ccflags-$(CONFIG_SOUNDWIRE_GENERIC_ALLOCATION) +=
> > -DDEFAULT_SYMBOL_NAMESPACE=SDW_CORE
>
> Don't use ccflags, just use the correct MODULE_EXPORT_NS() tag instead.

The documentation [1] states

"
Defining namespaces for all symbols of a subsystem can be very verbose 
and may become hard to maintain. Therefore a default define 
(DEFAULT_SYMBOL_NAMESPACE) is been provided, that, if set, will become 
the default for all EXPORT_SYMBOL() and EXPORT_SYMBOL_GPL() macro 
expansions that do not specify a namespace.
"

If the ccflags option is not supported or no longer desired, it'd be 
worth updating the documentation for dummies like me. I took the wording 
as a hint to avoid using MODULE_EXPORT_NS.

> And "SDW_CORE" is odd, "SOUNDWIRE" instead?

'sdw' is the prefix used everywhere for SoundWire symbols.

[1] https://www.kernel.org/doc/html/latest/core-api/symbol-namespaces.html