* Re: [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST
2026-09-30 10:12 ` [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST FUJITA Tomonori
@ 2026-09-30 10:27 ` Miguel Ojeda
2026-09-30 10:33 ` Michal Wilczynski
2026-09-30 11:57 ` Uwe Kleine-König
2 siblings, 0 replies; 7+ messages in thread
From: Miguel Ojeda @ 2026-09-30 10:27 UTC (permalink / raw)
To: FUJITA Tomonori
Cc: fustini, guoren, ukleinek, wefu, a.hindborg, acourbot, aliceryhl,
bjorn3_gh, boqun, dakr, daniel.almeida, gary, linux-riscv, lossin,
m.wilczynski, ojeda, tamird, tmgross, work, linux-pwm,
rust-for-linux, FUJITA Tomonori, stable
On Wed, Sep 30, 2026 at 12:13 PM FUJITA Tomonori <tomo@flapping.org> wrote:
>
> From: FUJITA Tomonori <fujita.tomonori@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@vger.kernel.org
> Reported-by: Andreas Hindborg <a.hindborg@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@kernel.org>
> Reviewed-by: Gary Guo <gary@garyguo.net>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@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
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^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST
2026-09-30 10:12 ` [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST FUJITA Tomonori
2026-09-30 10:27 ` Miguel Ojeda
@ 2026-09-30 10:33 ` Michal Wilczynski
2026-09-30 11:57 ` Uwe Kleine-König
2 siblings, 0 replies; 7+ messages in thread
From: Michal Wilczynski @ 2026-09-30 10:33 UTC (permalink / raw)
To: FUJITA Tomonori, fustini, guoren, ukleinek, wefu
Cc: a.hindborg, acourbot, aliceryhl, bjorn3_gh, boqun, dakr,
daniel.almeida, gary, linux-riscv, lossin, ojeda, tamird, tmgross,
work, linux-pwm, rust-for-linux, FUJITA Tomonori, stable
On 9/30/26 12:12, FUJITA Tomonori wrote:
> From: FUJITA Tomonori <fujita.tomonori@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@vger.kernel.org
> Reported-by: Andreas Hindborg <a.hindborg@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@kernel.org>
> Reviewed-by: Gary Guo <gary@garyguo.net>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
> ---
> v2:
> - Fix a typo in the commit message
> - Add Cc: stable, Reported-by and Closes tags
> - Add Reviewed-by tags from Andreas and Gary
> - Rebase on v7.3-rc5
>
> v1: https://lore.kernel.org/all/20260929095612.1072417-1-tomo@flapping.org/
> ---
> drivers/pwm/Kconfig | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 729776086879..abecd95b0c3c 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -772,7 +772,7 @@ config PWM_TEGRA
>
> config PWM_TH1520
> tristate "TH1520 PWM support"
> - depends on ARCH_THEAD || COMPILE_TEST
> + depends on ARCH_THEAD || (COMPILE_TEST && 64BIT)
> depends on RUST
> depends on HAS_IOMEM && COMMON_CLK
> select RUST_PWM_ABSTRACTIONS
>
> base-commit: 72d3fcf802c45d00b300f25b848a93c3a2bd7c7e
Reviewed-by: Michal Wilczynski <m.wilczynski@samsung.com>
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^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST
2026-09-30 10:12 ` [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST FUJITA Tomonori
2026-09-30 10:27 ` Miguel Ojeda
2026-09-30 10:33 ` Michal Wilczynski
@ 2026-09-30 11:57 ` Uwe Kleine-König
2026-09-30 22:02 ` FUJITA Tomonori
2 siblings, 1 reply; 7+ messages in thread
From: Uwe Kleine-König @ 2026-09-30 11:57 UTC (permalink / raw)
To: FUJITA Tomonori
Cc: fustini, guoren, wefu, a.hindborg, acourbot, aliceryhl, bjorn3_gh,
boqun, dakr, daniel.almeida, gary, linux-riscv, lossin,
m.wilczynski, ojeda, tamird, tmgross, work, linux-pwm,
rust-for-linux, FUJITA Tomonori, stable
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On Wed, Sep 30, 2026 at 07:12:57PM +0900, FUJITA Tomonori wrote:
> From: FUJITA Tomonori <fujita.tomonori@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@vger.kernel.org
> Reported-by: Andreas Hindborg <a.hindborg@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@kernel.org>
> Reviewed-by: Gary Guo <gary@garyguo.net>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
> ---
> v2:
> - Fix a typo in the commit message
> - Add Cc: stable, Reported-by and Closes tags
> - Add Reviewed-by tags from Andreas and Gary
> - Rebase on v7.3-rc5
>
> v1: https://lore.kernel.org/all/20260929095612.1072417-1-tomo@flapping.org/
> ---
> drivers/pwm/Kconfig | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 729776086879..abecd95b0c3c 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -772,7 +772,7 @@ config PWM_TEGRA
>
> config PWM_TH1520
> tristate "TH1520 PWM support"
> - depends on ARCH_THEAD || COMPILE_TEST
> + depends on ARCH_THEAD || (COMPILE_TEST && 64BIT)
> depends on RUST
> depends on HAS_IOMEM && COMMON_CLK
> select RUST_PWM_ABSTRACTIONS
Can't we do better than that? For C code the right thing to do is to use
one of the div helpers instead of a plain / for types bigger than long.
Best regards
Uwe
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^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST
2026-09-30 11:57 ` Uwe Kleine-König
@ 2026-09-30 22:02 ` FUJITA Tomonori
2026-10-01 6:27 ` Uwe Kleine-König
0 siblings, 1 reply; 7+ messages in thread
From: FUJITA Tomonori @ 2026-09-30 22:02 UTC (permalink / raw)
To: ukleinek
Cc: tomo, fustini, guoren, wefu, a.hindborg, acourbot, aliceryhl,
bjorn3_gh, boqun, dakr, daniel.almeida, gary, linux-riscv, lossin,
m.wilczynski, ojeda, tamird, tmgross, work, linux-pwm,
rust-for-linux, fujita.tomonori, stable
On Wed, 30 Sep 2026 13:57:31 +0200
Uwe Kleine-König <ukleinek@kernel.org> wrote:
>> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
>> index 729776086879..abecd95b0c3c 100644
>> --- a/drivers/pwm/Kconfig
>> +++ b/drivers/pwm/Kconfig
>> @@ -772,7 +772,7 @@ config PWM_TEGRA
>>
>> config PWM_TH1520
>> tristate "TH1520 PWM support"
>> - depends on ARCH_THEAD || COMPILE_TEST
>> + depends on ARCH_THEAD || (COMPILE_TEST && 64BIT)
>> depends on RUST
>> depends on HAS_IOMEM && COMMON_CLK
>> select RUST_PWM_ABSTRACTIONS
>
> Can't we do better than that? For C code the right thing to do is to use
> one of the div helpers instead of a plain / for types bigger than long.
Indeed. Rust code already uses some div helpers. However, the kernel
crate does not have Rust wrappers for the helpers this driver needs,
such as mul_u64_u64_div_u64(), so we need to add them first. The
changes would be too large for stable.
So how about merging this as a fix? I will work on patches to use div
helpers in the driver.
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST
2026-09-30 22:02 ` FUJITA Tomonori
@ 2026-10-01 6:27 ` Uwe Kleine-König
2026-10-01 9:07 ` FUJITA Tomonori
0 siblings, 1 reply; 7+ messages in thread
From: Uwe Kleine-König @ 2026-10-01 6:27 UTC (permalink / raw)
To: FUJITA Tomonori
Cc: fustini, guoren, wefu, a.hindborg, acourbot, aliceryhl, bjorn3_gh,
boqun, dakr, daniel.almeida, gary, linux-riscv, lossin,
m.wilczynski, ojeda, tamird, tmgross, work, linux-pwm,
rust-for-linux, fujita.tomonori, stable
[-- Attachment #1.1: Type: text/plain, Size: 1800 bytes --]
Hello,
On Thu, Oct 01, 2026 at 07:02:15AM +0900, FUJITA Tomonori wrote:
> On Wed, 30 Sep 2026 13:57:31 +0200
> Uwe Kleine-König <ukleinek@kernel.org> wrote:
>
> >> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> >> index 729776086879..abecd95b0c3c 100644
> >> --- a/drivers/pwm/Kconfig
> >> +++ b/drivers/pwm/Kconfig
> >> @@ -772,7 +772,7 @@ config PWM_TEGRA
> >>
> >> config PWM_TH1520
> >> tristate "TH1520 PWM support"
> >> - depends on ARCH_THEAD || COMPILE_TEST
> >> + depends on ARCH_THEAD || (COMPILE_TEST && 64BIT)
> >> depends on RUST
> >> depends on HAS_IOMEM && COMMON_CLK
> >> select RUST_PWM_ABSTRACTIONS
> >
> > Can't we do better than that? For C code the right thing to do is to use
> > one of the div helpers instead of a plain / for types bigger than long.
>
> Indeed. Rust code already uses some div helpers. However, the kernel
> crate does not have Rust wrappers for the helpers this driver needs,
> such as mul_u64_u64_div_u64(), so we need to add them first. The
> changes would be too large for stable.
>
> So how about merging this as a fix? I will work on patches to use div
> helpers in the driver.
Fine, then let me just wonder about the expression you chose, that makes
it look as if 64BIT was only needed for COMPILE_TEST.
How about making this
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 729776086879..4cc2911a0673 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -774,6 +774,7 @@ config PWM_TH1520
tristate "TH1520 PWM support"
depends on ARCH_THEAD || COMPILE_TEST
depends on RUST
+ depends on 64BIT # no 64bit division available on 32 bit builds
depends on HAS_IOMEM && COMMON_CLK
select RUST_PWM_ABSTRACTIONS
help
instead?
Best regards
Uwe
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^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST
2026-10-01 6:27 ` Uwe Kleine-König
@ 2026-10-01 9:07 ` FUJITA Tomonori
0 siblings, 0 replies; 7+ messages in thread
From: FUJITA Tomonori @ 2026-10-01 9:07 UTC (permalink / raw)
To: ukleinek
Cc: tomo, fustini, guoren, wefu, a.hindborg, acourbot, aliceryhl,
bjorn3_gh, boqun, dakr, daniel.almeida, gary, linux-riscv, lossin,
m.wilczynski, ojeda, tamird, tmgross, work, linux-pwm,
rust-for-linux, fujita.tomonori, stable
On Thu, 1 Oct 2026 08:27:45 +0200
Uwe Kleine-König <ukleinek@kernel.org> wrote:
>> > Can't we do better than that? For C code the right thing to do is to use
>> > one of the div helpers instead of a plain / for types bigger than long.
>>
>> Indeed. Rust code already uses some div helpers. However, the kernel
>> crate does not have Rust wrappers for the helpers this driver needs,
>> such as mul_u64_u64_div_u64(), so we need to add them first. The
>> changes would be too large for stable.
>>
>> So how about merging this as a fix? I will work on patches to use div
>> helpers in the driver.
>
> Fine, then let me just wonder about the expression you chose, that makes
> it look as if 64BIT was only needed for COMPILE_TEST.
>
> How about making this
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 729776086879..4cc2911a0673 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -774,6 +774,7 @@ config PWM_TH1520
> tristate "TH1520 PWM support"
> depends on ARCH_THEAD || COMPILE_TEST
> depends on RUST
> + depends on 64BIT # no 64bit division available on 32 bit builds
> depends on HAS_IOMEM && COMMON_CLK
> select RUST_PWM_ABSTRACTIONS
> help
>
> instead?
Yeah, it's cleaner.
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^ permalink raw reply [flat|nested] 7+ messages in thread