[U-Boot] [PATCH] pinctrl: renesas: Fix linker error when PINCTRL_PFC=n

[Eugeniu Rosca]

On Tue, Apr 02, 2019 at 05:28:43PM +0200, Marek Vasut wrote:
> On 4/2/19 5:17 PM, Dirk Behme wrote:
> > On 02.04.19 15:34, Marek Vasut wrote:
> >> On 4/2/19 3:18 PM, Eugeniu Rosca wrote:
> >>> With CONFIG_PINCTRL_PFC=n, aarch64-linux-gnu-ld reports:
> >>>
> >>> -----8<-----
> >>>    LD      u-boot
> >>> drivers/gpio/built-in.o: In function `rcar_gpio_request':
> >>> drivers/gpio/gpio-rcar.c:128: undefined reference to
> >>> `sh_pfc_config_mux_for_gpio'
> >>> -----8<-----
> >>>
> >>> Fix it in the least intrusive way and *avoid* ifdefs in the *.c code.
> >>>
> >>> Some recent Linux commits sharing the same approach:
> >>>   -
> >>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=23222f8f8dce
> >>>
> >>>     ("acpi, nfit: Add function to look up nvdimm device and provide
> >>> SMBIOS handle")
> >>>   -
> >>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5f143af7501e
> >>>
> >>>     ("spi: make OF helper available for others")
> >>>   -
> >>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bccd06223f21
> >>>
> >>>     ("IB/uverbs: Add UVERBS_ATTR_FLAGS_IN to the specs language")
> >>>
> >>> Fixes: f6e545a73f88 ("pfc: rmobile: Add hook to configure pin as GPIO")
> >>> Reported-by: Dirk Behme <dirk.behme at de.bosch.com>
> >>> Signed-off-by: Eugeniu Rosca <erosca at de.adit-jv.com>
> >>
> >> Does CONFIG_PINCTRL_PFC=n produce a bootable binary ?
> > 
> > 
> > Why not? Main memory, boot device and UART are configured before U-Boot,
> > no?
> 
> It depends on what is running before U-Boot, so not necessarily.
> 
> And speaking of boot device, consider the case where the system runs
> from eMMC and uses the HS200/HS400 modes, which need to switch bus mode
> using the pinmux driver.
> 
> Is there a real-world use case where you would want to disable the
> pinmux driver ? And what is the benefit of that, except that it would
> cause all kinds of weird problems.

My H3ULCB-KF boots just fine [1] with CONFIG_PINCTRL_PFC=n, but I
personally don't have any use-case which I need to fulfill on a
Renesas reference design by disabling PFC.

Rather, the motivation here is to ensure U-Boot builds fine with as
many randconfig results as possible, which is a standard practice in
Linux. I personally favor my solution, but I am also open minded if
the linker error is avoided by introducing a direct/reverse dependency
between PFC and another relevant R-Car3 Kconfig symbol.

[1] U-Boot 2019.04-rc4-00100-g03ece61db8 (Apr 02 2019 - 17:23:57 +0200)

CPU: Renesas Electronics R8A7795 rev 2.0
Model: Renesas H3ULCB board based on r8a7795 ES2.0+
DRAM:  3.9 GiB
MMC:   gpio at e6055000: set_value: error: gpio gpio at e60550001 not reserved
Can't set regulator : regulator-vccq-sdhi0 gpio to: 1
sd at ee100000: 0, sd at ee140000: 1
Loading Environment from MMC... OK
In:    serial at e6e88000
Out:   serial at e6e88000
Err:   serial at e6e88000
Net:   gpio at e6052000: set_value: error: gpio gpio at e605200010 not reserved
gpio at e6052000: set_value: error: gpio gpio at e605200010 not reserved
eth0: ethernet at e6800000
Hit any key to stop autoboot:  0 

> -- 
> Best regards,
> Marek Vasut

Best regards,
Eugeniu.