[PATCH v7 04/22] lib: Makefile: build crc7.c when CONFIG_MMC_SPI

[Heinrich Schuchardt]

Am May 2, 2020 11:47:10 AM UTC schrieb Bin Meng <bmeng.cn at gmail.com>:
>Hi Heinrich,
>
>On Sat, May 2, 2020 at 6:30 PM Heinrich Schuchardt <xypron.glpk at gmx.de>
>wrote:
>>
>> On 5/2/20 12:06 PM, Pragnesh Patel wrote:
>> > When build U-Boot SPL, meet an issue of undefined reference to
>> > 'crc7' for drivers/mmc/mmc_spi.c, so let's compile crc7.c when
>> > CONFIG_MMC_SPI selected.
>> >
>> > Signed-off-by: Pragnesh Patel <pragnesh.patel at sifive.com>
>> > Reviewed-by: Jagan Teki <jagan at amarulasolutions.com>
>> > Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
>> > ---
>> >  common/spl/Kconfig  | 6 ++++++
>> >  drivers/mmc/Kconfig | 1 +
>> >  lib/Makefile        | 1 +
>> >  3 files changed, 8 insertions(+)
>> >
>> > diff --git a/common/spl/Kconfig b/common/spl/Kconfig
>> > index ef5bf66696..d1f0e6bc4c 100644
>> > --- a/common/spl/Kconfig
>> > +++ b/common/spl/Kconfig
>> > @@ -401,6 +401,12 @@ config SPL_CRC32_SUPPORT
>> >         for detected accidental image corruption. For secure
>applications you
>> >         should consider SHA1 or SHA256.
>> >
>> > +config SPL_CRC7_SUPPORT
>> > +     bool "Support CRC7"
>> > +     help
>> > +       Enable CRC7 hashing for drivers which are using in SPL.
>> > +       This is a 32-bit checksum value that can be used to verify
>images.
>> > +
>> >  config SPL_MD5_SUPPORT
>> >       bool "Support MD5"
>> >       depends on SPL_FIT
>> > diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
>> > index 8f0df568b9..139599072a 100644
>> > --- a/drivers/mmc/Kconfig
>> > +++ b/drivers/mmc/Kconfig
>> > @@ -49,6 +49,7 @@ if MMC
>> >  config MMC_SPI
>> >       bool "Support for SPI-based MMC controller"
>> >       depends on DM_MMC && DM_SPI
>> > +     select SPL_CRC7_SUPPORT if SPL
>> >       help
>> >         This selects SPI-based MMC controllers.
>> >         If you have an MMC controller on a SPI bus, say Y here.
>> > diff --git a/lib/Makefile b/lib/Makefile
>> > index c6f862b0c2..fcd934857f 100644
>> > --- a/lib/Makefile
>> > +++ b/lib/Makefile
>> > @@ -80,6 +80,7 @@ endif
>> >
>> >  ifdef CONFIG_SPL_BUILD
>> >  obj-$(CONFIG_SPL_YMODEM_SUPPORT) += crc16.o
>> > +obj-$(CONFIG_SPL_CRC7_SUPPORT) += crc7.o
>>
>> crc7.o is not needed in main U-Boot if MMC_SPI is not selected.
>>
>> So instead of adding a new configuration variable simply correct the
>> existing line in lib/Makefile
>>
>> -obj-y += crc7.o
>> +obj-$(CONFIG_MMC_SPI) += crc7.o
>
>This looks incorrect to me. CRC7 can be useful for other drivers too.
>It should not depend on CONFIG_MMC_SPI.

Using this argument you would always compile everything. Compiling files that are not used is simply a waste of CPU time.

Following your argument. you could also always compile crc7.c for SPL and hope the compiler will eliminate it.

Either way we do not need a new config symbol.

Best regards

Heinrich

>
>>
>> and move that line inside lib/Makefile so that is does not depend on
>> CONFIG_SPL_BUILD.
>>
>
>Regards,
>Bin