Hi Arnd,
On Wed, Feb 28, 2018 at 11:08:54PM +0100, Arnd Bergmann wrote:
> On Wed, Feb 28, 2018 at 10:47 PM, Baruch Siach <bar...@tkos.co.il> wrote:
> > Thanks for the fix.
> >
> > On Wed, Feb 28, 2018 at 02:48:08PM +0100, Arnd Bergmann wrote:
> >> When the firmware driver is a loadable module, the gpio driver cannot be
> >> built-in:
> >>
> >> drivers/gpio/gpio-raspberrypi-exp.o: In function `rpi_exp_gpio_set':
> >> gpio-raspberrypi-exp.c:(.text+0xb4): undefined reference to
> >> `rpi_firmware_property'
> >> drivers/gpio/gpio-raspberrypi-exp.o: In function `rpi_exp_gpio_get':
> >> gpio-raspberrypi-exp.c:(.text+0x1ec): undefined reference to
> >> `rpi_firmware_property'
> >> drivers/gpio/gpio-raspberrypi-exp.o: In function
> >> `rpi_exp_gpio_get_direction':
> >> gpio-raspberrypi-exp.c:(.text+0x360): undefined reference to
> >> `rpi_firmware_property'
> >> drivers/gpio/gpio-raspberrypi-exp.o: In function
> >> `rpi_exp_gpio_get_polarity':
> >> gpio-raspberrypi-exp.c:(.text+0x4d4): undefined reference to
> >> `rpi_firmware_property'
> >> drivers/gpio/gpio-raspberrypi-exp.o: In function `rpi_exp_gpio_dir_out':
> >> gpio-raspberrypi-exp.c:(.text+0x670): undefined reference to
> >> `rpi_firmware_property'
> >> drivers/gpio/gpio-raspberrypi-exp.o:gpio-raspberrypi-exp.c:(.text+0x7fc):
> >> more undefined references to `rpi_firmware_property' follow
> >> drivers/gpio/gpio-raspberrypi-exp.o: In function `rpi_exp_gpio_dir_in':
> >> drivers/gpio/gpio-raspberrypi-exp.o: In function `rpi_exp_gpio_probe':
> >> gpio-raspberrypi-exp.c:(.text+0x93c): undefined reference to
> >> `rpi_firmware_get'
> >>
> >> We already have a Kconfig dependency for it, but when compile-testing, it
> >> is disregarded.
> >>
> >> This changes the dependency so that compile-testing is only done when the
> >> firmware driver is completely disabled.
> >
> > What about the CONFIG_ARCH_BCM2835=y case? The combination of
> > CONFIG_GPIO_RASPBERRYPI_EXP=y and CONFIG_RASPBERRYPI_FIRMWARE=m is still
> > valid. Wouldn't that break the build?
> >
> > Isn't there a way in Kconfig to force CONFIG_GPIO_RASPBERRYPI_EXP=m when
> > CONFIG_RASPBERRYPI_FIRMWARE=m?
>
> The problem I ran into only happens with CONFIG_ARCH_BCM2835=y to
> start with. My fix handles that case correctly, it forces
> CONFIG_GPIO_RASPBERRYPI_EXP to be either 'n' or 'm'
> when CONFIG_RASPBERRYPI_FIRMWARE=m.
Thanks for the explanation.
> > What about 'depends on m || RASPBERRYPI_FIRMWARE=y'?
>
> That would be (slightly) wrong, it would force CONFIG_GPIO_RASPBERRYPI_EXP
> to be 'm' even if RASPBERRYPI_FIRMWARE=n.
>
> > Grepping around I also found this:
> >
> > drivers/power/supply/Kconfig: depends on USB_GADGET || !USB_GADGET # if
> > USB_GADGET=m, this can't be 'y'
>
> That is what I did here as well, except the !RASPBERRYPI_FIRMWARE
> only applies for COMPILE_TEST.
>
> > And this:
> >
> > drivers/infiniband/Kconfig: depends on m || IPV6 != m
>
> This is a less common way to express it. The idiomatic
> Kconfig expression here would be 'depends on IPV6 || !IPV6'.
I find this way much easier to understand. Without the comment I would never
have guessed what 'USB_GADGET || !USB_GADGET' actually means. And indeed no
comment is needed in the infiniband case.
> >> Fixes: a98d90e7d588 ("gpio: raspberrypi-exp: Driver for RPi3 GPIO expander
> >> via mailbox service")
> >> Signed-off-by: Arnd Bergmann <a...@arndb.de>
> >> ---
> >> drivers/gpio/Kconfig | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> >> index 2ecd2adbaec6..52a8b0a6f4e1 100644
> >> --- a/drivers/gpio/Kconfig
> >> +++ b/drivers/gpio/Kconfig
> >> @@ -126,7 +126,7 @@ config GPIO_RASPBERRYPI_EXP
> >> tristate "Raspberry Pi 3 GPIO Expander"
> >> default RASPBERRYPI_FIRMWARE
> >> depends on OF_GPIO
> >> - depends on (ARCH_BCM2835 && RASPBERRYPI_FIRMWARE) || COMPILE_TEST
> >> + depends on (ARCH_BCM2835 && RASPBERRYPI_FIRMWARE) || (COMPILE_TEST
> >> && !RASPBERRYPI_FIRMWARE)
> >
> > This is really non-obvious. An inline comment here might help, IMO.
>
> How about
>
> # RASPBERRYPI_FIRMWARE is only available for ARCH_BCM2835, but we want
> to
> # allow compile-testing when it is disabled
>
> ?
The module vs built-in aspect is missing. That is the non-obvious part.
baruch
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