From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1517484967; cv=none; d=google.com; s=arc-20160816; b=A0mubakyaL2beYwMiQ4qPzDPLfr5VDv4EAZV4JaP3nuoGHcNtg4TK/G07yWYG1K6SQ tu30O4OMGieSIkujKkujscQaWPBNdVbLu3PbRFm9eduGxTaCdXGZNMXqRrE94as2kQuV /pKghQVwmPKTi3xXCDO21Rof2zpbfQiLtH5cmNdP43yjWQRe7jSl4aIqQ7AsIzqexn8E Eq00W8NIqkOkvmFABhyfzK7EZFl4DjKPwxtxT1SXpBDrrsH3X3S2jpSfIG0TgRK2CBwK kChZuPuhBwbc+OpeTE1DZadFcQq4LNB+ThR0KeVZ7cxwsQDAMIf9Z88TfHKNfdfmMT+2 P9yA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature :arc-authentication-results; bh=PMrojZ+EC7QQSJjYcQ4qgqKNtyna5iWciwcCfTCxaUY=; b=Qov0T8Qcx9/zR3GormN2O67PdvwEeLWlK96K8beabmjdTSmMNJZunbvZkoeX1mGH6j bv1ockNKmhXmeyz1B66Hl/get7Hb3V/aKrgdcjQaaaPTsWI+NUGhR9Olm6G60QnHnBzr dYpSCfWJVgyinf+1zA8PQU5ET6ZpAkC62M1RtSFH4wkVX+UKGlTxkeXXvgVREy8A/b8d N2UFMF/1/oIqxNEMmlLImo1M+Qu0wodPX1MrBFkdd600K60T2hJkvG9TAX3lmXyMRpv0 T5V/vUOI9RY+C53nQA4xfhVoXJHMOliKV1SA++PAbvoFyb2Wt1GnLRqpkriihMpIxFgr 6VUw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=C74MxRjH; spf=pass (google.com: domain of daniel.thompson@linaro.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=daniel.thompson@linaro.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=C74MxRjH; spf=pass (google.com: domain of daniel.thompson@linaro.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=daniel.thompson@linaro.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org X-Google-Smtp-Source: AH8x225rIYcKjfkiNEtGdrAR9jOQSNrFt0Zz07gyR8yeOO0Vg2M51UZgfhDTzzl9Zz+LCAPr8oTd/Q== Date: Thu, 1 Feb 2018 11:36:04 +0000 From: Daniel Thompson To: Jani Nikula Cc: Aishwarya Pant , Milo Kim , linux-fbdev@vger.kernel.org, Bartlomiej Zolnierkiewicz , Jingoo Han , Jonathan Corbet , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Julia Lawall , Greg KH , Lee Jones Subject: Re: [PATCH 1/5] backlight: lp8788: document sysfs attributes Message-ID: <20180201113604.kcue6auuivud52qz@oak.lan> References: <6523e26889d3dd65e90ea27c0d302a95aeb9da8b.1516978005.git.aishpant@gmail.com> <20180131110727.rmmwyqzwozwhda6z@oak.lan> <878tceckli.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <878tceckli.fsf@intel.com> User-Agent: NeoMutt/20170113 (1.7.2) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1590666949916676069?= X-GMAIL-MSGID: =?utf-8?q?1591198317332550194?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, Jan 31, 2018 at 01:51:21PM +0200, Jani Nikula wrote: > On Wed, 31 Jan 2018, Daniel Thompson wrote: > > On Fri, Jan 26, 2018 at 08:20:08PM +0530, Aishwarya Pant wrote: > >> Add documentation for sysfs interfaces of lp8788 backlight driver by > >> looking through the code and the git commit history. > >> > >> Signed-off-by: Aishwarya Pant > >> --- > >> Documentation/ABI/testing/sysfs-class-backlight-lp8788 | 10 ++++++++++ > >> 1 file changed, 10 insertions(+) > >> create mode 100644 Documentation/ABI/testing/sysfs-class-backlight-lp8788 > >> > >> diff --git a/Documentation/ABI/testing/sysfs-class-backlight-lp8788 b/Documentation/ABI/testing/sysfs-class-backlight-lp8788 > >> new file mode 100644 > >> index 000000000000..c0e565c8d63d > >> --- /dev/null > >> +++ b/Documentation/ABI/testing/sysfs-class-backlight-lp8788 > >> @@ -0,0 +1,10 @@ > >> +sysfs interface for Texas Instruments lp8788 mfd backlight driver > >> +----------------------------------------------------------------- > >> + > >> +What: /sys/class/backlight//bl_ctl_mode > >> +Date: Feb, 2013 > >> +KernelVersion: v3.10 > >> +Contact: Milo Kim > >> +Description: > >> + (RO) Displays whether the brightness is controlled by the PWM > >> + input("PWM based") or the I2C register("Register based"). > > > > I rather dislike drivers with this type of "bonus" sysfs controls. I'm > > struggling to come up with any reason why the userspace would want to > > read this control (and I think bl_ctl_mode gets the fewest hits after > > searching with google hits of any search I've tried) . It looks to me > > like this is debug information that should never have gone into sysfs > > at all. > > Agreed. I think the same holds for the other extra sysfs attributes. At > worst, having these prevents the backlight class from adding the names > later on, which is just backwards. The problem is that they do exist... For controls which appear to be misplaced debug attributes I think I am happy to nuke the values entirely. It is extremely improbable that any userspace will notice. Unfortunately some of the controls look like they could be poked by an custom userspace so I'm quite so confident about nuking these ones...and if we don't nuke we should document (so thanks Aishwarya!). Daniel.