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

Maximilian Luz
2023-04-05T09:34:10Z

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@gmail.com>

> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
> 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