linux-kernel - Re: [PATCH v2 3/6] ARM: dts: rockchip: remove interrupts properties from pwm nodes rv1108.dtsi

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Message-ID: <31b5ff50-afe5-b446-7d3c-943d148814d8@gmail.com>
Date:   Mon, 12 Apr 2021 12:03:26 +0200
From:   Johan Jonker <jbx6244@...il.com>
To:     wens@...nel.org
Cc:     Heiko Stübner <heiko@...ech.de>,
        Rob Herring <robh+dt@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Lee Jones <lee.jones@...aro.org>, linux-pwm@...r.kernel.org,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/6] ARM: dts: rockchip: remove interrupts properties
 from pwm nodes rv1108.dtsi

On 4/12/21 5:15 AM, Chen-Yu Tsai wrote:
> On Sun, Apr 11, 2021 at 9:11 PM Johan Jonker <jbx6244@...il.com> wrote:
>>
>> A test with the command below gives this error:
>>
>> /arch/arm/boot/dts/rv1108-evb.dt.yaml:
>> pwm@...80000: 'interrupts' does not match any of the regexes:
>> 'pinctrl-[0-9]+'
>>
>> "interrupts" is an undocumented property, so remove them
>> from pwm nodes in rv1108.dtsi.
>>
>> make ARCH=arm dtbs_check
>> DT_SCHEMA_FILES=Documentation/devicetree/bindings/pwm/pwm-rockchip.yaml
>>
>> Signed-off-by: Johan Jonker <jbx6244@...il.com>
> 
> Given that the interrupts were specified, meaning they are wired up in hardware,
> shouldn't the solution be to add the interrupts property to the binding instead?
> 
> After all, the device tree describes the actual hardware, not just what the
> implementations need.
> 
> ChenYu
> 

Hi,

The question of what to do with it was asked in version 1, but no answer
was given, so I made a proposal.
The device tree description should be complete, but also as lean as
possible. If someone manages to sneak in undocumented properties without
reason then the ultimate consequence should be removal I think.

Not sure about the (missing?) rv1108 TRM, but for rk3328 the interrupt
is used for:

PWM_INTSTS 0x0040 W 0x00000000 Interrupt Status Register
  Channel Interrupt Polarity Flag
    This bit is used in capture mode in order to identify the
    transition of the input waveform when interrupt is generated.
  Channel Interrupt Status
    Interrupt generated

PWM_INT_EN 0x0044 W 0x00000000 Interrupt Enable Register
  Channel Interrupt Enable

Is there any current realistic use/setup for it to convince rob+dt this
should be added to pwm-rockchip.yaml?

The rk3328 interrupt rkpwm_int seems shared between channels, but only
included to pwm3. What is the proper way for that?

Johan