From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Subject: Re: [PATCH 3.9] Driver for 7-segment displays connected over GPIOs Date: Mon, 7 Jan 2013 18:07:08 +0100 Message-ID: <20130107180708.2ffc1540@skate> References: <1357576928-29133-1-git-send-email-thomas.petazzoni@free-electrons.com> <20130107164845.GA2911@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130107164845.GA2911-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Greg Kroah-Hartman Cc: Lior Amsalem , Andrew Lunn , Jason Cooper , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org Dear Greg Kroah-Hartman, On Mon, 7 Jan 2013 08:48:45 -0800, Greg Kroah-Hartman wrote: > If you ever add/remove/modify sysfs files, you have to also do the same > for the Documentation/ABI/ files as well, please redo that in this patch > series. Sure. > But, the bigger question is, why is this a kernel driver at all? Can't > you do this from userspace today without any new kernel code? Indeed, it can be done from userspace since we're just controlling GPIOs. Having a kernel driver allows to describe this device in the Device Tree, like all other devices, and have it "magically" appear, with a convenient user-space interface. Not having a kernel driver means that gazillions of applications re-invent the same piece of code over and over again, have to hardcode the GPIO numbers for a given piece of hardware, while the kernel abstract all of this very nicely. Thanks, Thomas -- Thomas Petazzoni, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com