Re: [PATCH v2] iio/adc: ingenic: fix (MIPS) ingenic-adc build errors

[Randy Dunlap]

On 11/12/21 9:29 AM, Jonathan Cameron wrote:
> On Tue,  9 Nov 2021 18:37:55 -0800
> Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote:
>
> > MIPS does not always provide clk*() interfaces and there are no
> > always-present stubs for them, so depending on "MIPS || COMPILE_TEST"
> > is not strong enough to prevent build errors.
> >
> > Likewise MACH_INGENIC_SOC || COMPILE_TEST is not strong enough
> > since if only COMPILE_TEST=y (with some other MIPS MACH_ or CPU or
> > BOARD setting), there are still the same build errors.
> >
> > It looks like depending on MACH_INGENIC is the only thing that is
> > sufficient here in order to prevent build errors.
> >
> > mips-linux-ld: drivers/iio/adc/ingenic-adc.o: in function `jz4770_adc_init_clk_div':
> > ingenic-adc.c:(.text+0xe4): undefined reference to `clk_get_parent'
> > mips-linux-ld: drivers/iio/adc/ingenic-adc.o: in function `jz4725b_adc_init_clk_div':
> > ingenic-adc.c:(.text+0x1b8): undefined reference to `clk_get_parent'
> >
> > Fixes: 1a78daea107d ("IIO: add Ingenic JZ47xx ADC driver.")
> > Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Cc: Artur Rojek <contact@xxxxxxxxxxxxxx>
> > Cc: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> > Cc: linux-mips@xxxxxxxxxxxxxxx
> > Cc: Jonathan Cameron <jic23@xxxxxxxxxx>
> > Cc: Lars-Peter Clausen <lars@xxxxxxxxxx>
> > Cc: linux-iio@xxxxxxxxxxxxxxx
> > Cc: Florian Fainelli <f.fainelli@xxxxxxxxx>
> > Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
>
> I'm a bit confused.  There are stubs in include/linux/clk.h for these.
> Why do those not apply here? Are these platforms built with CONFIG_CLK but
> don't provide all the functions?
>
> That sounds highly error prone and rather defeats the object of the
> stubs.  Could we either provide the missing stubs, or solve this some other
> way.  I'm not keen to massively cut the build coverage this driver is getting
> by dropping COMPILE_TEST if there is any route to avoid doing so.

I'm all for that (above), but it's a mess.

> Based on the guess than any platform with clks must be able to turn them on
> I grepped for int clk_enable() and there seem to be only two possiblities
> bcm63xx and lantiq as sources of the build breakage.

CONFIG_BCM63XX=y
# CONFIG_MACH_INGENIC_SOC is not set
CONFIG_INGENIC_ADC=y
CONFIG_HAVE_CLK=y


According to the build error messages (above), clk_get_parent()
is missing. Looking at <linux/clk.h>, for CONFIG_HAVE_CLK=y,
there is a prototype for clk_get_parent(), and if CONFIG_HAVE_CLK
is not set, there is a stub for it.

Now look at drivers/clk/clk.c and drivers/clk/Makefile:

clk_get_parent() is defined in clk.c, which is built when
CONFIG_COMMON_CLK=y, but that is not set in this .config file.

CONFIG_HAVE_CLK=y, but that doesn't get clk_get_parent()
compiled.

So to me it is a disparity or incongruity between HAVE_CLK and COMMON_CLK.

Russell- do you have any suggestions for how to straighten
this out?


> Jonathan
>
> > ---
> > v2: use MACH_INGENIC instead of MACH_INGENIC_SOC (thanks, Paul)
> >
> >   drivers/iio/adc/Kconfig |    2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > --- linux-next-20211105.orig/drivers/iio/adc/Kconfig
> > +++ linux-next-20211105/drivers/iio/adc/Kconfig
> > @@ -501,7 +501,7 @@ config INA2XX_ADC
> >   
> >   config INGENIC_ADC
> >   	tristate "Ingenic JZ47xx SoCs ADC driver"
> > -	depends on MIPS || COMPILE_TEST
> > +	depends on MACH_INGENIC
> >   	select IIO_BUFFER
> >   	help
> >   	  Say yes here to build support for the Ingenic JZ47xx SoCs ADC unit.


--
~Randy