From: "Uwe Kleine-König" <ukleinek@kernel.org>
To: FUJITA Tomonori <tomo@flapping.org>
Cc: fustini@kernel.org, guoren@kernel.org, wefu@redhat.com,
a.hindborg@kernel.org, acourbot@nvidia.com,
aliceryhl@google.com, bjorn3_gh@protonmail.com,
boqun@kernel.org, dakr@kernel.org, daniel.almeida@collabora.com,
gary@garyguo.net, linux-riscv@lists.infradead.org,
lossin@kernel.org, m.wilczynski@samsung.com, ojeda@kernel.org,
tamird@kernel.org, tmgross@umich.edu, work@onurozkan.dev,
linux-pwm@vger.kernel.org, rust-for-linux@vger.kernel.org,
fujita.tomonori@gmail.com, stable@vger.kernel.org
Subject: Re: [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST
Date: Thu, 1 Oct 2026 08:27:45 +0200 [thread overview]
Message-ID: <ar38qq0q8f2Vecuw@monoceros> (raw)
In-Reply-To: <20261001.070215.521963012921142699.tomo@flapping.org>
[-- 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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WARNING: multiple messages have this Message-ID (diff)
From: "Uwe Kleine-König" <ukleinek@kernel.org>
To: FUJITA Tomonori <tomo@flapping.org>
Cc: fustini@kernel.org, guoren@kernel.org, wefu@redhat.com,
a.hindborg@kernel.org, acourbot@nvidia.com,
aliceryhl@google.com, bjorn3_gh@protonmail.com,
boqun@kernel.org, dakr@kernel.org, daniel.almeida@collabora.com,
gary@garyguo.net, linux-riscv@lists.infradead.org,
lossin@kernel.org, m.wilczynski@samsung.com, ojeda@kernel.org,
tamird@kernel.org, tmgross@umich.edu, work@onurozkan.dev,
linux-pwm@vger.kernel.org, rust-for-linux@vger.kernel.org,
fujita.tomonori@gmail.com, stable@vger.kernel.org
Subject: Re: [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST
Date: Thu, 1 Oct 2026 08:27:45 +0200 [thread overview]
Message-ID: <ar38qq0q8f2Vecuw@monoceros> (raw)
In-Reply-To: <20261001.070215.521963012921142699.tomo@flapping.org>
[-- Attachment #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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next prev parent reply other threads:[~2026-10-01 6:28 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20260930101334eucas1p2ec64abcf499a296767711f13ad70c486@eucas1p2.samsung.com>
2026-09-30 10:12 ` [PATCH v2] pwm: th1520: Fix 32-bit build with COMPILE_TEST FUJITA Tomonori
2026-09-30 10:12 ` FUJITA Tomonori
2026-09-30 10:27 ` Miguel Ojeda
2026-09-30 10:27 ` Miguel Ojeda
2026-09-30 10:33 ` Michal Wilczynski
2026-09-30 10:33 ` Michal Wilczynski
2026-09-30 11:57 ` Uwe Kleine-König
2026-09-30 11:57 ` Uwe Kleine-König
2026-09-30 22:02 ` FUJITA Tomonori
2026-09-30 22:02 ` FUJITA Tomonori
2026-10-01 6:27 ` Uwe Kleine-König [this message]
2026-10-01 6:27 ` Uwe Kleine-König
2026-10-01 9:07 ` FUJITA Tomonori
2026-10-01 9:07 ` FUJITA Tomonori
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