Re: [PATCH v12 05/11] edma: config: Enable config options for EDMA

[Joel A Fernandes]

On Fri, Jun 21, 2013 at 9:00 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> On Friday 21 June 2013, Joel A Fernandes wrote:
>> >> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
>> >> index b1c66a4..7d58cd9 100644
>> >> --- a/arch/arm/Kconfig
>> >> +++ b/arch/arm/Kconfig
>> >> @@ -841,6 +841,7 @@ config ARCH_DAVINCI
>> >>       select HAVE_IDE
>> >>       select NEED_MACH_GPIO_H
>> >>       select TI_PRIV_EDMA
>> >> +     select DMADEVICES
>> >
>> > It is generally a bad idea to force select on something that can be
>> > enabled using menuconfig. Unless used carefully, select causes "unmet
>> > direct dependency" warnings which folks are already fighting hard to
>> > fix. This leads to what Russell referred in the past as "select madness" [1]
>>
>> Are you concerned with bloat issues? I know your point of view but the idea
>> was to build these options by default for these platforms even though
>> in some cases
>> it might not be used. I have seen folks including myself select the wrong
>> option. Having the build system automatically select the correct option for the
>> most common cases can be very useful I feel and not require manual
>> configuration.
>
> For defaults, you should use the defconfig, not 'select' in Kconfig.
>
> A lot of the 'select' statements are actually wrong because they
> do not take dependencies into account where A selects B but not C,
> and B depends on C, which leads to broken builds when C is disabled
> by a user (or randconfig).

I haven't come across this problem but- are you saying there is a
shortcoming in Kbuild/Kconfig that selects an option even if its
dependency is not met?

The problem with defconfig is also too many options I feel for a common case.
CONFIG_DMADEVICES=y
CONFIG_TI_EDMA=y

Most if not all future OMAPs from will use EDMA. Why not we can be
explicit about it and just built it in anyway. If ARCH_OMAP and
DMADEVICES are selected, then we can just build EDMA in by default.

I agree maybe the option can be dropped from Davinci but I suggest
let's keep it for OMAP. Is that ok?

Thanks,
Joel
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