Re: [PATCH] drivers: bus: omap_interconnect: Fix rand-config build warning

[Santosh Shilimkar <santosh.shilimkar@ti.com>]

On Friday 26 October 2012 12:45 AM, Tony Lindgren wrote:
> * Santosh Shilimkar <santosh.shilimkar@ti.com> [121024 23:34]:
>> On Thursday 25 October 2012 06:12 AM, Tony Lindgren wrote:
>>> * Tony Lindgren <tony@atomide.com> [121024 17:36]:
>>>> * Santosh Shilimkar <santosh.shilimkar@ti.com> [121017 06:35]:
>>>>> (Looping Arnd and Olof)
>>>>>
>>>>> On Wednesday 17 October 2012 06:58 PM, Lokesh Vutla wrote:
>>>>>> When building omap_l3_noc/smx drivers as modules, the following
>>>>>> warning appears:
>>>>>>
>>>>>> CC [M]  drivers/bus/omap_l3_smx.o
>>>>>> drivers/bus/omap_l3_smx.c:291: warning: data definition has no type or storage class
>>>>>> drivers/bus/omap_l3_smx.c:291: warning: type defaults to 'int' in declaration of 'postcore_initcall_sync'
>>>>>> drivers/bus/omap_l3_smx.c:291: warning: parameter names (without types) in function declaration
>>>>>> drivers/bus/omap_l3_smx.c:287: warning: 'omap3_l3_init' defined but not used
>>>>>> CC [M]  drivers/bus/omap_l3_noc.o
>>>>>> drivers/bus/omap_l3_noc.c:260: warning: data definition has no type or storage class
>>>>>> drivers/bus/omap_l3_noc.c:260: warning: type defaults to 'int' in declaration of 'arch_initcall_sync'
>>>>>> drivers/bus/omap_l3_noc.c:260: warning: parameter names (without types) in function declaration
>>>>>> drivers/bus/omap_l3_noc.c:256: warning: 'omap4_l3_init' defined but not used
>>>>>>
>>>>>> Adding module_init() and macros in omap_l3_noc/smx drivers when building
>>>>>> as modules to remove the above warning.
>>>>>>
>>>>>> Reported-by: Tony Lindgren <tony@atomide.com>
>>>>>> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
>>>>>> ---
>>>>> Thanks for the fix Lokesh. Looks fine to me.
>>>>>
>>>>> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
>>>>
>>>> Looks like nobody else has picked this up so I'll queue this along
>>>> with few other omap warnings and regressions.
>>>
>>> Hmm actually this might require some more discussion. If we make
>>> it use regular initcalls, then the ugly ifdefs can be left
>>> out. Is there a reason to init this early, can't we just use regular
>>> initcalls?
>>>
>> I thought about it. The whole reason we want interconnect errors
>> enabled early in the boot to avoid bad accesses issued on
>> interconnect
>> in early boot by various init codes. We managed to discovered many
>> init sequence issues where the a driver is trying to access registers
>> when clocks are not active, or drivers are using bad mapping. At times
>> these errors gets un-noticed because of the behavior of interconnect
>> and later causes serious issues. Leaving the driver init late in the
>> boot means we can't catch any of the issues happen till the L3 driver
>> init happens.
>
> OK yeah that makes sense. How about let's just make it
> just postcore_initcall instead of postcore_initcall_sync?
>
_sync was added by purpose since the driver has depedency on
the hwmod initialisation which is postcore_initcall. Without
the sync, we open the race condition and the l3 driver
registration will fail.

> In include/linux/module.h we have:
>
> ...
> #else /* MODULE */
>
> /* Don't use these in loadable modules, but some people do... */
> #define early_initcall(fn)              module_init(fn)
> #define core_initcall(fn)               module_init(fn)
> #define postcore_initcall(fn)           module_init(fn)
> ...
>
> While the postcore_initcall_sync does not have those.
>
> No idea what the current plan is, but I sort of remember reading
> that the _sync versions are going away at some point anyways?
>
I have no idea either. As mentioned sync was added to avoid the
race. If and when _sync is removed, something should come as an
alternative to avoid initcall completion dependencies for the one
which falls in same group.

Regards,
Santosh