From: "Xuyang Dong" <dongxuyang@eswincomputing.com>
To: "Krzysztof Kozlowski" <krzk@kernel.org>
Cc: ukleinek@kernel.org, robh@kernel.org, krzk+dt@kernel.org,
conor+dt@kernel.org, ben-linux@fluff.org,
ben.dooks@codethink.co.uk, p.zabel@pengutronix.de,
linux-pwm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, ningyu@eswincomputing.com,
linmin@eswincomputing.com, xuxiang@eswincomputing.com,
wangguosheng@eswincomputing.com, pinkesh.vaghela@einfochips.com
Subject: Re: Re: [PATCH v3 1/2] dt-bindings: pwm: dwc: add reset optional
Date: Tue, 14 Apr 2026 10:52:38 +0800 (GMT+08:00) [thread overview]
Message-ID: <23dd507b.5335.19d89e7b99c.Coremail.dongxuyang@eswincomputing.com> (raw)
In-Reply-To: <20260403-glossy-industrious-pug-4f2b2c@quoll>
> >
> > The DesignWare PWM controller provides separate reset signals for each
>
> So one controller has signals. Plural, right? Then why do you define
> only one reset signal?
>
Hi Krzysztof,
There are two reset signals matching the two clocks, so maxItems is set to 2.
> > clock domain, as specified in the hardware documentation. Without
> > asserting and deasserting these resets during probe, PWM outputs may
> > remain in an undefined state after system reboot.
> >
> > To address this, the driver now supports an optional 'resets' property.
>
> This is binding change, not driver.
>
> > A full reset is performed only when no PWM channel is enabled, as
> > determined by reading the enable bit in each channel's control register.
>
> Do you describe hardware or driver behavior? This is not a change about
> driver. Describe the hardware here - what is expected with that reset.
>
> > This allows safe coexistence with bootloaders that have already
> > configured active PWM channels.
>
The improvement commit message for the next version will be revised
as follows:
The DesignWare PWM includes separate reset signals dedicated to each clock
domain:
The presetn signal resets logic in pclk domain.
The timer_N_resetn signal resets logic in the timer_N_clk domain.
The resets are active-low.
In the next version, we will address the changes as described above.
Best regards,
Xuyang Dong
next prev parent reply other threads:[~2026-04-14 2:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-02 9:17 [PATCH v3 0/2] Update designware pwm driver dongxuyang
2026-04-02 9:18 ` [PATCH v3 1/2] dt-bindings: pwm: dwc: add reset optional dongxuyang
2026-04-03 7:27 ` Krzysztof Kozlowski
2026-04-14 2:52 ` Xuyang Dong [this message]
2026-04-02 9:19 ` [PATCH v3 2/2] pwm: dwc: add of/platform support dongxuyang
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