Jérôme Pouiller <jerome.pouiller@xxxxxxxxxx> writes:
> On Tuesday 22 December 2020 16:02:38 CET Kalle Valo wrote:
>> Jerome Pouiller <Jerome.Pouiller@xxxxxxxxxx> writes:
>>
>> > From: Jérôme Pouiller <jerome.pouiller@xxxxxxxxxx>
>> >
>> > Signed-off-by: Jérôme Pouiller <jerome.pouiller@xxxxxxxxxx>
>>
>> [...]
>>
>> > +wfx-$(CONFIG_SPI) += bus_spi.o
>> > +wfx-$(subst m,y,$(CONFIG_MMC)) += bus_sdio.o
>>
>> Why this subst? And why only for MMC?
>
> CONFIG_SPI is a boolean (y or empty). The both values make senses.
>
> CONFIG_MMC is a tristate (y, m or empty). The substitution above
> ensure that bus_sdio.o will included in wfx.ko if CONFIG_MMC is 'm'
> ("wfx-$(CONFIG_MMC) += bus_sdio.o" wouldn't make the job).
>
> You may want to know what it happens if CONFIG_MMC=m while CONFIG_WFX=y.
> This line in Kconfig prevents to compile wfx statically if MMC is a
> module:
> depends on MMC || !MMC # do not allow WFX=y if MMC=m
Ok, thanks for explaining this.
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