[PATCH v5 0/3] Implement Send and Sync for clk

[PATCH v5 0/3] Implement Send and Sync for clk

[Alice Ryhl]

The Clk type is thread-safe, so let's mark it as thread-safe in the type
system. This lets us get rid of hacks in drivers.

For Stephen's clk tree.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
Changes in v5:
- Rebase on v7.0-rc1.
- Pick up Reviewed-by tags.
- Link to v4: https://lore.kernel.org/r/20260113-clk-send-sync-v4-0-712bc7d94a79@google.com

Changes in v4:
- Pick up Reviewed-by tags.
- Link to v3: https://lore.kernel.org/r/20251218-clk-send-sync-v3-0-e48b2e2f1eac@google.com

Changes in v3:
- Rebase on v6.19-rc1.
- Pick up tags.
- Add fix for pwm driver as well.
- Link to v2: https://lore.kernel.org/r/20251020-clk-send-sync-v2-0-44ab533ae084@google.com

Changes in v2:
- Rebase on v6.18-rc1.
- Add patch to tyr driver.
- Link to v1: https://lore.kernel.org/r/20250904-clk-send-sync-v1-1-48d023320eb8@google.com

---
Alice Ryhl (3):
      rust: clk: implement Send and Sync
      tyr: remove impl Send/Sync for TyrData
      pwm: th1520: remove impl Send/Sync for Th1520PwmDriverData

 drivers/gpu/drm/tyr/driver.rs | 12 ------------
 drivers/pwm/pwm_th1520.rs     | 15 ---------------
 rust/kernel/clk.rs            |  7 +++++++
 3 files changed, 7 insertions(+), 27 deletions(-)
---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20250904-clk-send-sync-3cfa7f4e1ce2

Best regards,
-- 
Alice Ryhl <aliceryhl@google.com>

[PATCH v5 1/3] rust: clk: implement Send and Sync

[Alice Ryhl]

These traits are required for drivers to embed the Clk type in their own
data structures because driver data structures are usually required to
be Send. Since the Clk type is thread-safe, implement the relevant
traits.

Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/clk.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/rust/kernel/clk.rs b/rust/kernel/clk.rs
index 4059aff34d096264bc7f3c8bfcb39eb3f42725be..7abbd0767d8cff9f2561d1783a9a1d774a96d1fc 100644
--- a/rust/kernel/clk.rs
+++ b/rust/kernel/clk.rs
@@ -128,6 +128,13 @@ mod common_clk {
     #[repr(transparent)]
     pub struct Clk(*mut bindings::clk);
 
+    // SAFETY: It is safe to call `clk_put` on another thread than where `clk_get` was called.
+    unsafe impl Send for Clk {}
+
+    // SAFETY: It is safe to call any combination of the `&self` methods in parallel, as the
+    // methods are synchronized internally.
+    unsafe impl Sync for Clk {}
+
     impl Clk {
         /// Gets [`Clk`] corresponding to a [`Device`] and a connection id.
         ///

-- 
2.53.0.345.g96ddfc5eaa-goog

[PATCH v5 2/3] tyr: remove impl Send/Sync for TyrData

[Alice Ryhl]

Now that clk implements Send and Sync, we no longer need to manually
implement these traits for TyrData. Thus remove the implementations.

The comment also mentions the regulator. However, the regulator had the
traits added in commit 9a200cbdb543 ("rust: regulator: implement Send
and Sync for Regulator<T>"), which is already in mainline.

Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
 drivers/gpu/drm/tyr/driver.rs | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/drivers/gpu/drm/tyr/driver.rs b/drivers/gpu/drm/tyr/driver.rs
index beeffe36b6cb068f2a87129872b37cbea4fb2010..e833e9f537b0225368ca10f5bc71b2612b0befa5 100644
--- a/drivers/gpu/drm/tyr/driver.rs
+++ b/drivers/gpu/drm/tyr/driver.rs
@@ -53,18 +53,6 @@ pub(crate) struct TyrData {
     pub(crate) gpu_info: GpuInfo,
 }
 
-// Both `Clk` and `Regulator` do not implement `Send` or `Sync`, but they
-// should. There are patches on the mailing list to address this, but they have
-// not landed yet.
-//
-// For now, add this workaround so that this patch compiles with the promise
-// that it will be removed in a future patch.
-//
-// SAFETY: This will be removed in a future patch.
-unsafe impl Send for TyrData {}
-// SAFETY: This will be removed in a future patch.
-unsafe impl Sync for TyrData {}
-
 fn issue_soft_reset(dev: &Device<Bound>, iomem: &Devres<IoMem>) -> Result {
     regs::GPU_CMD.write(dev, iomem, regs::GPU_CMD_SOFT_RESET)?;
 

-- 
2.53.0.345.g96ddfc5eaa-goog

[PATCH v5 3/3] pwm: th1520: remove impl Send/Sync for Th1520PwmDriverData

[Alice Ryhl]

Now that clk implements Send and Sync, we no longer need to manually
implement these traits for Th1520PwmDriverData. Thus remove the
implementations.

Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Acked-by: Uwe Kleine-König <ukleinek@kernel.org>
Reviewed-by: Michal Wilczynski <m.wilczynski@samsung.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
 drivers/pwm/pwm_th1520.rs | 15 ---------------
 1 file changed, 15 deletions(-)

diff --git a/drivers/pwm/pwm_th1520.rs b/drivers/pwm/pwm_th1520.rs
index b0e24ee724e4501b812e5f9c7904b483bfe5e2dc..6cd6fa3d298484cbd84b88cfdd3244217855fa05 100644
--- a/drivers/pwm/pwm_th1520.rs
+++ b/drivers/pwm/pwm_th1520.rs
@@ -99,21 +99,6 @@ struct Th1520PwmDriverData {
     clk: Clk,
 }
 
-// This `unsafe` implementation is a temporary necessity because the underlying `kernel::clk::Clk`
-// type does not yet expose `Send` and `Sync` implementations. This block should be removed
-// as soon as the clock abstraction provides these guarantees directly.
-// TODO: Remove those unsafe impl's when Clk will support them itself.
-
-// SAFETY: The `devres` framework requires the driver's private data to be `Send` and `Sync`.
-// We can guarantee this because the PWM core synchronizes all callbacks, preventing concurrent
-// access to the contained `iomem` and `clk` resources.
-unsafe impl Send for Th1520PwmDriverData {}
-
-// SAFETY: The same reasoning applies as for `Send`. The PWM core's synchronization
-// guarantees that it is safe for multiple threads to have shared access (`&self`)
-// to the driver data during callbacks.
-unsafe impl Sync for Th1520PwmDriverData {}
-
 impl pwm::PwmOps for Th1520PwmDriverData {
     type WfHw = Th1520WfHw;
 

-- 
2.53.0.345.g96ddfc5eaa-goog

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Danilo Krummrich]

Hi Stephen,

On Mon Feb 23, 2026 at 11:08 AM CET, Alice Ryhl wrote:
> The Clk type is thread-safe, so let's mark it as thread-safe in the type
> system. This lets us get rid of hacks in drivers.
>
> For Stephen's clk tree.
>
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> ---
> Changes in v5:
> - Rebase on v7.0-rc1.
> - Pick up Reviewed-by tags.
> - Link to v4: https://lore.kernel.org/r/20260113-clk-send-sync-v4-0-712bc7d94a79@google.com
>
> Changes in v4:
> - Pick up Reviewed-by tags.
> - Link to v3: https://lore.kernel.org/r/20251218-clk-send-sync-v3-0-e48b2e2f1eac@google.com
>
> Changes in v3:
> - Rebase on v6.19-rc1.
> - Pick up tags.
> - Add fix for pwm driver as well.
> - Link to v2: https://lore.kernel.org/r/20251020-clk-send-sync-v2-0-44ab533ae084@google.com
>
> Changes in v2:
> - Rebase on v6.18-rc1.
> - Add patch to tyr driver.
> - Link to v1: https://lore.kernel.org/r/20250904-clk-send-sync-v1-1-48d023320eb8@google.com

Alice has resent this over the past three cycles, but it hasn't been picked up
yet. Please let me know if there are any concerns -- otherwise, I plan to take
it through the drm-rust tree in a few days.

Thanks,
Danilo

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Miguel Ojeda]

On Fri, Mar 20, 2026 at 12:43 PM Danilo Krummrich <dakr@kernel.org> wrote:
>
> Alice has resent this over the past three cycles, but it hasn't been picked up
> yet. Please let me know if there are any concerns -- otherwise, I plan to take
> it through the drm-rust tree in a few days.

+1, it will keep accumulating changes otherwise. Alice asked me about
this one too; I can pick it up if needed too.

Cheers,
Miguel

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Maxime Ripard]

[-- Attachment #1: Type: text/plain, Size: 1512 bytes --]

Hi Danilo,

On Fri, Mar 20, 2026 at 12:43:47PM +0100, Danilo Krummrich wrote:
> Hi Stephen,
> 
> On Mon Feb 23, 2026 at 11:08 AM CET, Alice Ryhl wrote:
> > The Clk type is thread-safe, so let's mark it as thread-safe in the type
> > system. This lets us get rid of hacks in drivers.
> >
> > For Stephen's clk tree.
> >
> > Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> > ---
> > Changes in v5:
> > - Rebase on v7.0-rc1.
> > - Pick up Reviewed-by tags.
> > - Link to v4: https://lore.kernel.org/r/20260113-clk-send-sync-v4-0-712bc7d94a79@google.com
> >
> > Changes in v4:
> > - Pick up Reviewed-by tags.
> > - Link to v3: https://lore.kernel.org/r/20251218-clk-send-sync-v3-0-e48b2e2f1eac@google.com
> >
> > Changes in v3:
> > - Rebase on v6.19-rc1.
> > - Pick up tags.
> > - Add fix for pwm driver as well.
> > - Link to v2: https://lore.kernel.org/r/20251020-clk-send-sync-v2-0-44ab533ae084@google.com
> >
> > Changes in v2:
> > - Rebase on v6.18-rc1.
> > - Add patch to tyr driver.
> > - Link to v1: https://lore.kernel.org/r/20250904-clk-send-sync-v1-1-48d023320eb8@google.com
> 
> Alice has resent this over the past three cycles, but it hasn't been picked up
> yet. Please let me know if there are any concerns -- otherwise, I plan to take
> it through the drm-rust tree in a few days.

Stephen hasn't really been active lately, but Brian (in Cc) has been
trying to pick up the patches falling through the cracks. It looks like
such a candidate to me.

Maxime

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Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Brian Masney]

Hi Danilo and Alice,

On Sat, Mar 21, 2026 at 2:17 PM Maxime Ripard <mripard@kernel.org> wrote:
> On Fri, Mar 20, 2026 at 12:43:47PM +0100, Danilo Krummrich wrote:
> > On Mon Feb 23, 2026 at 11:08 AM CET, Alice Ryhl wrote:
> > > The Clk type is thread-safe, so let's mark it as thread-safe in the type
> > > system. This lets us get rid of hacks in drivers.
> > >
> > > For Stephen's clk tree.
> > >
> > > Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> > > ---
> > > Changes in v5:
> > > - Rebase on v7.0-rc1.
> > > - Pick up Reviewed-by tags.
> > > - Link to v4: https://lore.kernel.org/r/20260113-clk-send-sync-v4-0-712bc7d94a79@google.com
> > >
> > > Changes in v4:
> > > - Pick up Reviewed-by tags.
> > > - Link to v3: https://lore.kernel.org/r/20251218-clk-send-sync-v3-0-e48b2e2f1eac@google.com
> > >
> > > Changes in v3:
> > > - Rebase on v6.19-rc1.
> > > - Pick up tags.
> > > - Add fix for pwm driver as well.
> > > - Link to v2: https://lore.kernel.org/r/20251020-clk-send-sync-v2-0-44ab533ae084@google.com
> > >
> > > Changes in v2:
> > > - Rebase on v6.18-rc1.
> > > - Add patch to tyr driver.
> > > - Link to v1: https://lore.kernel.org/r/20250904-clk-send-sync-v1-1-48d023320eb8@google.com
> >
> > Alice has resent this over the past three cycles, but it hasn't been picked up
> > yet. Please let me know if there are any concerns -- otherwise, I plan to take
> > it through the drm-rust tree in a few days.
>
> Stephen hasn't really been active lately, but Brian (in Cc) has been
> trying to pick up the patches falling through the cracks. It looks like
> such a candidate to me.

I'm planning to send another clk pull at the end of this week and I'll
include this series.

Brian

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Miguel Ojeda]

On Mon, Mar 23, 2026 at 1:16 AM Brian Masney <bmasney@redhat.com> wrote:
>
> I'm planning to send another clk pull at the end of this week and I'll
> include this series.

Thanks Brian!

Cheers,
Miguel

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Brian Masney]

Hi Danilo / Alice / Miguel,

On Sun, Mar 22, 2026 at 8:15 PM Brian Masney <bmasney@redhat.com> wrote:
> On Sat, Mar 21, 2026 at 2:17 PM Maxime Ripard <mripard@kernel.org> wrote:
> > On Fri, Mar 20, 2026 at 12:43:47PM +0100, Danilo Krummrich wrote:
> > > On Mon Feb 23, 2026 at 11:08 AM CET, Alice Ryhl wrote:
> > > > The Clk type is thread-safe, so let's mark it as thread-safe in the type
> > > > system. This lets us get rid of hacks in drivers.
> > > >
> > > > For Stephen's clk tree.
> > > >
> > > > Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> > > > ---
> > > > Changes in v5:
> > > > - Rebase on v7.0-rc1.
> > > > - Pick up Reviewed-by tags.
> > > > - Link to v4: https://lore.kernel.org/r/20260113-clk-send-sync-v4-0-712bc7d94a79@google.com
> > > >
> > > > Changes in v4:
> > > > - Pick up Reviewed-by tags.
> > > > - Link to v3: https://lore.kernel.org/r/20251218-clk-send-sync-v3-0-e48b2e2f1eac@google.com
> > > >
> > > > Changes in v3:
> > > > - Rebase on v6.19-rc1.
> > > > - Pick up tags.
> > > > - Add fix for pwm driver as well.
> > > > - Link to v2: https://lore.kernel.org/r/20251020-clk-send-sync-v2-0-44ab533ae084@google.com
> > > >
> > > > Changes in v2:
> > > > - Rebase on v6.18-rc1.
> > > > - Add patch to tyr driver.
> > > > - Link to v1: https://lore.kernel.org/r/20250904-clk-send-sync-v1-1-48d023320eb8@google.com
> > >
> > > Alice has resent this over the past three cycles, but it hasn't been picked up
> > > yet. Please let me know if there are any concerns -- otherwise, I plan to take
> > > it through the drm-rust tree in a few days.
> >
> > Stephen hasn't really been active lately, but Brian (in Cc) has been
> > trying to pick up the patches falling through the cracks. It looks like
> > such a candidate to me.
>
> I'm planning to send another clk pull at the end of this week and I'll
> include this series.

Stephen came on the list and started to merge this things this week. I
was going to collect up more patches for him if he wasn't around, and
intended to include this. However, since he's starting to collect
things, I'm not going to send him a clk pull today.

It's up to you if you want to send this in via drm-rust or wait for Stephen.

Brian

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Miguel Ojeda]

On Fri, Mar 27, 2026 at 2:19 PM Brian Masney <bmasney@redhat.com> wrote:
>
> Stephen came on the list and started to merge this things this week. I
> was going to collect up more patches for him if he wasn't around, and
> intended to include this. However, since he's starting to collect
> things, I'm not going to send him a clk pull today.
>
> It's up to you if you want to send this in via drm-rust or wait for Stephen.

I guess it depends if he plans to pick it up this cycle or not.

If he doesn't, then it may be best to just go forward with your
Acked-bys -- Danilo can pick it up if DRM needs it in their branch,
otherwise I can pick it up.

Thanks!

Cheers,
Miguel

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Brian Masney]

On Fri, Mar 27, 2026 at 11:00 AM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
> On Fri, Mar 27, 2026 at 2:19 PM Brian Masney <bmasney@redhat.com> wrote:
> >
> > Stephen came on the list and started to merge this things this week. I
> > was going to collect up more patches for him if he wasn't around, and
> > intended to include this. However, since he's starting to collect
> > things, I'm not going to send him a clk pull today.
> >
> > It's up to you if you want to send this in via drm-rust or wait for Stephen.
>
> I guess it depends if he plans to pick it up this cycle or not.
>
> If he doesn't, then it may be best to just go forward with your
> Acked-bys -- Danilo can pick it up if DRM needs it in their branch,
> otherwise I can pick it up.

I am not a clk maintainer, so I can't leave an Acked-by for you to
pick this up unfortunately. I've been quite active in the clk
subsystem though the last 6 months or so.

Brian

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Danilo Krummrich]

On Fri Mar 27, 2026 at 4:17 PM CET, Brian Masney wrote:
> I am not a clk maintainer, so I can't leave an Acked-by for you to
> pick this up unfortunately. I've been quite active in the clk
> subsystem though the last 6 months or so.

I'm not involved in the CLK subsystem, but maybe it would be a good chance to
offer stepping up as co-maintainer (also given that Michael seems to be inactive
for a couple of years now). :)

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Brian Masney]

On Fri, Mar 27, 2026 at 11:42 AM Danilo Krummrich <dakr@kernel.org> wrote:
> On Fri Mar 27, 2026 at 4:17 PM CET, Brian Masney wrote:
> > I am not a clk maintainer, so I can't leave an Acked-by for you to
> > pick this up unfortunately. I've been quite active in the clk
> > subsystem though the last 6 months or so.
>
> I'm not involved in the CLK subsystem, but maybe it would be a good chance to
> offer stepping up as co-maintainer (also given that Michael seems to be inactive
> for a couple of years now). :)

I mentioned to Stephen at the last LPC in Tokyo that I am interested
in becoming a clk co-maintainer. I've sent him some git pulls for some
of my work the last few development cycles, and he's pulled them. For
this development cycle, I collected up some patches from others that I
feel are ready, however I didn't hear back from Stephen yet:

https://lore.kernel.org/linux-clk/abLV9vjYxXsKciHW@redhat.com/

He separately pulled some of that work via the posted patches into
clk-next this week. I don't know if there was something he didn't like
in my git pull.

To be honest, I initially helped with reviews trying to free up time
for him to give feedback about my work to address some long-standing
issues related to clk scaling that affect DRM and sound:

https://lore.kernel.org/linux-clk/20260323-clk-scaling-v7-0-8e7193dc9405@redhat.com/
The kunit tests in patch 2 and 4 clearly show the issues. (I'm working
on some fixes to this series right now based on feedback from
Sashiko.)

I've become more interested in the clk subsystem as I learn more about
it. There are other improvements that I am willing to make to the clk
subsystem, however the current situation has been quite challenging to
be honest. I will help with the linux-clk subsystem for the long term
if there is the possibility of me eventually becoming a co-maintainer.
Stephen can have veto power over what goes in.

Brian

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Miguel Ojeda]

On Fri, Mar 27, 2026 at 4:17 PM Brian Masney <bmasney@redhat.com> wrote:
>
> I am not a clk maintainer, so I can't leave an Acked-by for you to
> pick this up unfortunately. I've been quite active in the clk
> subsystem though the last 6 months or so.

In that case, I could take your Acked-by as an active contributor of
clk if you are willing to provide it, i.e. with the "# Suffix"
notation I introduced a year ago:

  https://docs.kernel.org/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by

  cd9123eeb224 ("docs: submitting-patches: clarify Acked-by and
introduce "# Suffix"")

i.e. Acked-bys can nowadays be provided by other stakeholders apart
from maintainers, e.g. people with domain knowledge, userspace
reviewers of uAPI patches, key users and so on.

Especially so since you offered to be a co-maintainer long term, so I
think having your Acked-by is way better that having no tag at all :)

Cheers,
Miguel

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Miguel Ojeda]

On Fri, Mar 27, 2026 at 5:54 PM Brian Masney <bmasney@redhat.com> wrote:
>
> I mentioned to Stephen at the last LPC in Tokyo that I am interested
> in becoming a clk co-maintainer.

Thanks for the context, that sounds great -- more maintainers and
reviewers are needed in the kernel.

But, of course, it is up to Stephen.

Another possibility Stephen could perhaps like if he doesn't want a
co-maintainer for everything is having a sub-maintainer for the Rust
side, possibly in a sub-entry (e.g. "COMMON CLK FRAMEWORK [RUST]",
i.e. with the usual square brackets we use for that), assuming you are
interested in that.

It is an approach that we have seen works well, because it is usually
a win-win for maintainers that cannot commit time to review new Rust
stuff, i.e. they get more people in their subsystem, they can use the
opportunity to learn Rust (assuming they don't know it yet) and they
can assess how often Rust changes are needed, yet they still control
the changes (e.g. in cases a change on both sides needs to happen at
once).

[ In any case, I don't know the context behind all this -- if I can
help with anything, please let me know. ]

Thanks!

Cheers,
Miguel

Re: [PATCH v5 0/3] Implement Send and Sync for clk

[Brian Masney]

On Fri, Mar 27, 2026 at 1:28 PM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
=> On Fri, Mar 27, 2026 at 4:17 PM Brian Masney <bmasney@redhat.com> wrote:
> >
> > I am not a clk maintainer, so I can't leave an Acked-by for you to
> > pick this up unfortunately. I've been quite active in the clk
> > subsystem though the last 6 months or so.
>
> In that case, I could take your Acked-by as an active contributor of
> clk if you are willing to provide it, i.e. with the "# Suffix"
> notation I introduced a year ago:
>
>   https://docs.kernel.org/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by
>
>   cd9123eeb224 ("docs: submitting-patches: clarify Acked-by and
> introduce "# Suffix"")
>
> i.e. Acked-bys can nowadays be provided by other stakeholders apart
> from maintainers, e.g. people with domain knowledge, userspace
> reviewers of uAPI patches, key users and so on.
>
> Especially so since you offered to be a co-maintainer long term, so I
> think having your Acked-by is way better that having no tag at all :)

Sure...

Acked-by: Brian Masney <bmasney@redhat.com> # Active contributor to clk