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From:   Gottfried Haider <gottfried.haider@gmail.com>
Date:   Fri, 28 Sep 2018 17:19:18 -0700
Message-ID: <CAPoCmY+mNYSV8gq7VCcSJHDpmoq-i7SDJ6uQ5VbLpMZB=b0waQ@mail.gmail.com>
Subject: Re: [RESEND PATCH] Revert "pwm: Set class for exported channels in sysfs"
To:     Thierry Reding <thierry.reding@gmail.com>
Cc:     fabrice.gasnier@st.com, stefan.wahren@i2se.com,
        gohai@sukzessiv.net,
        H Hartley Sweeten <hsweeten@visionengravers.com>,
        loic.pallardy@st.com, broonie@kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-rpi-kernel@lists.infradead.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-pwm@vger.kernel.org, michal.vokac@ysoft.com
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Sender: linux-kernel-owner@vger.kernel.org
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Hello Thierry & Fabrice,

>> Still, it is possible to send uevent (KOBJ_CHANGE) on pwmchipN device,
>> to notify of a change, e.g. pwmX channel being exported/unexported.

I tested this patch, and I am happy to report that it works with the
udev rule that Raspbian (Raspberry Pi's Debian derivative) has in
place:

SUBSYSTEM=="pwm*", PROGRAM="/bin/sh -c '\
        chown -R root:gpio /sys/class/pwm && chmod -R 770 /sys/class/pwm;\
        chown -R root:gpio
/sys/devices/platform/soc/*.pwm/pwm/pwmchip* && chmod -R 770
/sys/devices/platform/soc/*.pwm/pwm/pwmchip*\
'"


So while I can't comment on the uevent semantics, it would solve what
the original patch attempted to enable (non-root use of pwm).

Tested-by: Gottfried Haider <gottfried.haider@gmail.com>

Best,
Gottfried