linux-kernel - Re: [PATCH v13 2/4] arm64: dts: fsl: librem5: Add a device tree for the Librem5 devkit

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Message-ID: <9626cd324eaaab2b49c37cf3c824aa5e@www.akkea.ca>
Date:   Thu, 23 May 2019 14:52:56 -0700
From:   Angus Ainslie <angus@...ea.ca>
To:     Pavel Machek <pavel@....cz>
Cc:     angus.ainslie@...i.sm, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-kernel-owner@...r.kernel.org
Subject: Re: [PATCH v13 2/4] arm64: dts: fsl: librem5: Add a device tree for  the Librem5 devkit

Hi Pavel,


On 2019-05-23 12:19, Pavel Machek wrote:
> Hi!
> 
>> This is for the development kit board for the Librem 5. The current 
>> level
>> of support yields a working console and is able to boot userspace from
>> the network or eMMC.
>> 
>> Additional subsystems that are active :
> 
>> - haptic motor
> 
> Haptic motor is not a LED. It should be controlled by input subsystem.
> 
>> +	pwmleds {
>> +		compatible = "pwm-leds";
>> +
>> +		haptic {
>> +			label = "librem5::haptic";
>> +			pwms = <&pwm2 0 200000>;
>> +			active-low;
>> +			max-brightness = <255>;
>> +			power-supply = <&reg_3v3_p>;
>> +		};
>> +	};
> 
> You can take a look at N900, that has reasonable interface.
> 

I wanted to control the haptic with the pwm-vibra driver but 
"fsl,imx27-pwm" doesn't seem to respect the PWM_POLARITY_INVERTED flag 
so when I start the system the vibrator is full on.

I could use gpio-vibrator but that seemed like a waste when the device 
is connected to pwm.

I figured the using the pwm-leds interface was a reasonable compromise 
until I had an opportunity to make changes the the imx27-pwm driver.

Thanks
Angus


> Thanks,
> 										Pavel