Re: [PATCH V4 22/23] platform/surface: Disable for RISC-V

[Maximilian Luz]

On 4/4/23 20:20, Sunil V L wrote:
> With CONFIG_ACPI enabled for RISC-V, this driver gets enabled
> in allmodconfig build. However, RISC-V doesn't support sub-word
> atomics which is used by this driver. Due to this, the build fails
> with below error.
>
> In function ‘ssh_seq_next’,
>      inlined from ‘ssam_request_write_data’ at drivers/platform/surface/aggregator/controller.c:1483:8:
> ././include/linux/compiler_types.h:399:45: error: call to ‘__compiletime_assert_335’ declared with attribute error: BUILD_BUG failed
>    399 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>        |                                             ^
> ./include/linux/compiler.h:78:45: note: in definition of macro ‘unlikely’
>     78 | # define unlikely(x)    __builtin_expect(!!(x), 0)
>        |                                             ^
> ././include/linux/compiler_types.h:387:9: note: in expansion of macro ‘__compiletime_assert’
>    387 |         __compiletime_assert(condition, msg, prefix, suffix)
>        |         ^~~~~~~~~~~~~~~~~~~~
> ././include/linux/compiler_types.h:399:9: note: in expansion of macro ‘_compiletime_assert’
>    399 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>        |         ^~~~~~~~~~~~~~~~~~~
> ./include/linux/build_bug.h:39:37: note: in expansion of macro ‘compiletime_assert’
>     39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
>        |                                     ^~~~~~~~~~~~~~~~~~
> ./include/linux/build_bug.h:59:21: note: in expansion of macro ‘BUILD_BUG_ON_MSG’
>     59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
>        |                     ^~~~~~~~~~~~~~~~
> ./arch/riscv/include/asm/cmpxchg.h:335:17: note: in expansion of macro ‘BUILD_BUG’
>    335 |                 BUILD_BUG();                                            \
>        |                 ^~~~~~~~~
> ./arch/riscv/include/asm/cmpxchg.h:344:30: note: in expansion of macro ‘__cmpxchg’
>    344 |         (__typeof__(*(ptr))) __cmpxchg((ptr),                           \
>        |                              ^~~~~~~~~
> ./include/linux/atomic/atomic-instrumented.h:1916:9: note: in expansion of macro ‘arch_cmpxchg’
>   1916 |         arch_cmpxchg(__ai_ptr, __VA_ARGS__); \
>        |         ^~~~~~~~~~~~
> drivers/platform/surface/aggregator/controller.c:61:32: note: in expansion of macro ‘cmpxchg’
>     61 |         while (unlikely((ret = cmpxchg(&c->value, old, new)) != old)) {
>        |                                ^~~~~~~
>
> So, disable this driver for RISC-V even when ACPI is enabled for now.

CONFIG_SURFACE_PLATFORMS should be enabled for ARM64 || X86 || COMPILE_TEST only,
so I guess the issue only happens when compiling with the latter enabled?

I'm not aware of any current plans of MS to release RISC-V-based Surface
devices, so you could maybe also just explicitly disable CONFIG_SURFACE_PLATFORMS.
In any case, I don't see any issues with disabling the whole platform/surface
or only individual drivers for RISC-V, so for either solution:

Acked-by: Maximilian Luz <luzmaximilian@xxxxxxxxx>

> Signed-off-by: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>
> ---
>   drivers/platform/surface/aggregator/Kconfig | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/platform/surface/aggregator/Kconfig b/drivers/platform/surface/aggregator/Kconfig
> index c114f9dd5fe1..88afc38ffdc5 100644
> --- a/drivers/platform/surface/aggregator/Kconfig
> +++ b/drivers/platform/surface/aggregator/Kconfig
> @@ -4,7 +4,7 @@
>   menuconfig SURFACE_AGGREGATOR
>   	tristate "Microsoft Surface System Aggregator Module Subsystem and Drivers"
>   	depends on SERIAL_DEV_BUS
> -	depends on ACPI
> +	depends on ACPI && !RISCV
>   	select CRC_CCITT
>   	help
>   	  The Surface System Aggregator Module (Surface SAM or SSAM) is an