From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Reading /sys with side effects (was Re: [PATCH 1/2] Documentation: leds: Add description of LED Flash class extension) Date: Tue, 27 Jan 2015 23:37:08 +0100 Message-ID: <20150127221958.GA18993@amd> References: <1422346028-16739-1-git-send-email-j.anaszewski@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1422346028-16739-1-git-send-email-j.anaszewski@samsung.com> Sender: linux-leds-owner@vger.kernel.org To: Jacek Anaszewski , Greg KH , kernel list Cc: linux-leds@vger.kernel.org, devicetree@vger.kernel.org, kyungmin.park@samsung.com, b.zolnierkie@samsung.com, cooloney@gmail.com, rpurdie@rpsys.net, sakari.ailus@iki.fi, s.nawrocki@samsung.com List-Id: devicetree@vger.kernel.org Hi! > + - flash_fault - list of flash faults that may have occurred: > + * led-over-voltage - flash controller voltage to the flash LED > + has exceededthe limit specific to the flash controller > + * flash-timeout-exceeded - the flash strobe was still on when > + the timeout set by the user has expired; not all flash > + controllers may set this in all such conditions > + * controller-over-temperature - the flash controller has > + overheated > + * controller-short-circuit - the short circuit protection > + of the flash controller has been triggered > + * led-power-supply-over-current - current in the LED power > + supply has exceeded the limit specific to the flash > + controller > + * indicator-led-fault - the flash controller has detected > + a short or open circuit condition on the indicator LED > + * led-under-voltage - flash controller voltage to the flash > + LED has been below the minimum limit specific to > + the flash > + * controller-under-voltage - the input voltage of the flash > + controller is below the limit under which strobing the > + flash at full current will not be possible. The condition > + persists until this flag is no longer set > + * led-over-temperature - the temperature of the LED has exceeded > + its allowed upper limit > + > + Flash faults are cleared, if possible, by reading the attribute. That's bad. Now you can no longer present flash_fault file as readable to non-root users, and grep -ri foo /sys will interfere with your camera application. Bad interface, just fix it. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html