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

[Dirk Behme]

On 02.04.19 17:40, Eugeniu Rosca wrote:
> 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.


What's about people needing to do products based on these reference 
designs which have boot time and by this size requirements?

And having functions which are build time encapsulated with CONFIG_* 
but not their callers I simply would consider as a bug which needs to 
be fixed. Like you have done here, citing several kernel examples for 
this :)

Best regards

Dirk

> 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.
>