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

[Pragnesh Patel]

>-----Original Message-----
>From: Jagan Teki <jagan at amarulasolutions.com>
>Sent: 02 May 2020 21:04
>To: Heinrich Schuchardt <xypron.glpk at gmx.de>; Pragnesh Patel
><pragnesh.patel at sifive.com>; Bin Meng <bmeng.cn at gmail.com>
>Cc: U-Boot Mailing List <u-boot at lists.denx.de>; Atish Patra
><atish.patra at wdc.com>; Palmer Dabbelt <palmerdabbelt at google.com>; Paul
>Walmsley <paul.walmsley at sifive.com>; Troy Benjegerdes
><troy.benjegerdes at sifive.com>; Anup Patel <anup.patel at wdc.com>; Sagar
>Kadam <sagar.kadam at sifive.com>; Rick Chen <rick at andestech.com>; Peng
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>Goldschmidt <simon.k.r.goldschmidt at gmail.com>; Simon Glass
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>Takahiro <takahiro.akashi at linaro.org>; Marek Behún <marek.behun at nic.cz>
>Subject: Re: [PATCH v7 04/22] lib: Makefile: build crc7.c when
>CONFIG_MMC_SPI
>
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>On Sat, May 2, 2020 at 6:45 PM Heinrich Schuchardt <xypron.glpk at gmx.de>
>wrote:
>>
>> 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.
>
>This is one of the reasons I just suggested that the mark 'depends on
>MMC_SPI' at the very initial patch.
>
>Marking config SPL_CRC7_SUPPORT which depends on MMC_SPI would work
>for me.

@Jagan Teki I think MMC_SPI should be depend on or select SPL_CRC7_SUPPORT.
SPL_CRC7_SUPPORT is not depend on MMC_SPI.

@Heinrich Schuchardt Compiling crc7.o every time is not a good idea. I have 1 suggestion,
Can we make 1 Kconfig like

+config CRC7_SUPPORT
+	bool "Support CRC7"
+	help
+	  Enable CRC7 hashing for drivers.
+	  This is a 32-bit checksum value that can be used to verify images.

Which is common for U-Boot proper and U-Boot SPL and compile crc7

+ obj-$(CONFIG_CRC7_SUPPORT) += crc7.o

Any suggestions are welcome ?

>
>Jagan.