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

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Message-ID: <c8dfb12c-2394-3dfe-571d-dcc5fadb8dc2@linux.intel.com>
Date:   Mon, 16 Dec 2019 11:07:59 -0600
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     alsa-devel@...a-project.org, tiwai@...e.de,
        linux-kernel@...r.kernel.org,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        vkoul@...nel.org, broonie@...nel.org,
        srinivas.kandagatla@...aro.org, jank@...ence.com,
        slawomir.blauciak@...el.com, Sanyog Kale <sanyog.r.kale@...el.com>,
        Bard liao <yung-chuan.liao@...ux.intel.com>,
        Rander Wang <rander.wang@...ux.intel.com>
Subject: Re: [alsa-devel] [PATCH v4 08/15] soundwire: add initial definitions
 for sdw_master_device


>>>> 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.
> 
> It's supported, and works just fine.  It's just that you really don't
> have a ton of exports, right?  What's wrong with manually marking them?

I don't see a MODULE_EXPORT_NS so we'd have to change every single 
EXPORT_SYMBOL to EXPORT_SYMBOL_NS.

If we are talking about adding the namespaces just about the top-level 
functions used by Intel, yes we have less than 10 and since they were 
renamed it's no big deal.

But if we want to use this namespace for lower-level components of the 
SoundWire code, we have 17 exports in cadence_master.c and more than 27 
for the core parts. With the Makefile changes shared last week you'd 
have 3 changes, I find it more manageable but it's true that the 
information would be split with the IMPORT_NS in the code and the 
namespace definition in the Makefile.


>>> And "SDW_CORE" is odd, "SOUNDWIRE" instead?
>>
>> 'sdw' is the prefix used everywhere for SoundWire symbols.
> 
> Ok, I guess that ship has sailed :(

we can still use SOUNDWIRE for the namespaces, that'd be fine. you're 
right to call us on acronyms, it's a bad habit.