[PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST

[Miguel Ojeda]

On Wed, Sep 30, 2026 at 12:13 PM FUJITA Tomonori <tomo at flapping.org> wrote:
>
> From: FUJITA Tomonori <fujita.tomonori at gmail.com>
>
> Fix the following build error on 32-bit ARM with COMPILE_TEST:
>
>   ERROR: modpost: drivers/pwm/pwm_th1520.ko: symbol '__aeabi_uldivmod' undefined!
>
> The driver divides u64 values when it converts between nanoseconds and
> clock cycles. On 32-bit ARM, these divisions are compiled to calls to
> __aeabi_uldivmod, which the kernel does not provide.
>
> The TH1520 is a 64-bit RISC-V SoC, so the driver is only used on
> 64-bit kernels. There is no point in compile testing it on 32-bit.
> Limit COMPILE_TEST to 64BIT instead of changing the arithmetic to use
> the div64 helpers.
>
> Fixes: 3c180003dffb ("pwm: th1520: Fix missing Kconfig dependencies")
> Cc: stable at vger.kernel.org
> Reported-by: Andreas Hindborg <a.hindborg at kernel.org>
> Closes: https://rust-for-linux.zulipchat.com/#narrow/channel/291565-Help/topic/64bit.20division.20in.20.60pwm_th1520.2Ers.60/near/626825599
> Reviewed-by: Andreas Hindborg <a.hindborg at kernel.org>
> Reviewed-by: Gary Guo <gary at garyguo.net>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori at gmail.com>

Thanks Tomo!

If PWM wants me to pick it up for some reason, please let me know (I
don't plan at the moment to send a fixes PR, though).

Cheers,
Miguel