[PATCH v10 0/7] Rust Abstractions for PWM subsystem with TH1520 PWM driver

[Uwe Kleine-König]

Hello,

On Thu, Jul 10, 2025 at 06:58:41PM +0200, Michal Wilczynski wrote:
> On 7/10/25 17:25, Uwe Kleine-König wrote:
> > On Thu, Jul 10, 2025 at 03:48:08PM +0200, Michal Wilczynski wrote:
> >> On 7/10/25 15:10, Uwe Kleine-König wrote:
> >>> On Thu, Jul 10, 2025 at 10:42:07AM +0200, Michal Wilczynski wrote:
> >>>> On 7/7/25 11:48, Michal Wilczynski wrote:
> >>>>> The series is structured as follows:
> >>>>>  - Expose static function pwmchip_release.
> >>>
> >>> Is this really necessary? I didn't try to understand the requirements
> >>> yet, but I wonder about that. If you get the pwmchip from
> >>> __pwmchip_add() the right thing to do to release it is to call
> >>> pwmchip_remove(). Feels like a layer violation.
> >>
> >> It's required to prevent a memory leak in a specific, critical failure
> >> scenario. The sequence of events is as follows:
> >>
> >>     pwm::Chip::new() succeeds, allocating both the C struct pwm_chip and
> >>     the Rust drvdata.
> >>
> >>     pwm::Registration::register() (which calls pwmchip_add()) fails for
> >>     some reason.
> > 
> > If you called pwmchip_alloc() but not yet pwmchip_add(), the right
> > function to call for cleanup is pwmchip_put().
> > 
> >>     The ARef<Chip> returned by new() is dropped, its reference count
> >>     goes to zero, and our custom release_callback is called.
> >>
> >> [...]
> >>>>> ---
> >>>>> base-commit: 47753b5a1696283930a78aae79b29371f96f5bca
> >>>
> >>> I have problems applying this series and don't have this base commit in
> >>> my repo.
> >>
> >> Sorry for the confusion. Base commit doesn't exist in the mainline
> >> kernel or linux-next, cause I've added some dependecies for compilation,
> >> like IoMem for the driver (uploaded full branch on github [1]). The
> >> bindings however doesn't depend on anything that's not in linux-next.
> > 
> > The series didn't apply to my pwm/for-next branch.
> > 
> > Note that the base-commit should always be a publically known commit.
> > See the chapter about "Base Tree Information" in git-format-patch(1).
> 
> Hello Uwe,
> 
> Okay, thank you for the clarification. I understand the requirement for
> a public base commit.
> 
> My intention was to include the TH1520 driver primarily as a practical
> demonstration of the new abstractions. However the driver can't be
> merged as is, since it depends on the unmerged IoMem series and won't
> compile against a public commit.
> 
> I will rebase the series on pwm/for-next and drop the driver and its
> associated device tree patches for now. I'll send a new version
> containing just the core PWM abstraction patches, which apply cleanly.
> 
> I will resubmit the driver patches once their dependencies are available
> in a public tree.

If you base your tree on (say) v6.16-rc1, then add some Rust
dependencies up to 47753b5a1696283930a78aae79b29371f96f5bca and then add
your series, you just do:

	git format-patch --base v6.16-rc1 47753b5a1696283930a78aae79b29371f96f5bca..

. This results in a base-commit line that I (and maybe also build bots)
can use and a bunch of further lines listing the commits between
v6.16-rc1 and 47753b5a1696283930a78aae79b29371f96f5bca that might be
findable on lore.k.o.

Best regards
Uwe
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