From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Likely Subject: Re: [PATCH 3.9 1/3] misc: new driver for GPIO-connected 7-segment displays Date: Fri, 08 Feb 2013 22:38:22 +0000 Message-ID: <20130208223822.4204A3E2C27@localhost> References: <1357576928-29133-1-git-send-email-thomas.petazzoni@free-electrons.com> <201301071943.40074.arnd@arndb.de> <20130107205854.1f019816@skate> <201301072141.48487.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201301072141.48487.arnd-r2nGTMty4D4@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: Arnd Bergmann , Thomas Petazzoni Cc: Lior Amsalem , Andrew Lunn , Jason Cooper , Greg Kroah-Hartman , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On Mon, 7 Jan 2013 21:41:48 +0000, Arnd Bergmann wrote: > On Monday 07 January 2013, Thomas Petazzoni wrote: > > Dear Arnd Bergmann, > > > > On Mon, 7 Jan 2013 19:43:39 +0000, Arnd Bergmann wrote: > > > > > > .../devicetree/bindings/misc/gpio-7seg.txt | 18 +++ > > > > drivers/misc/Kconfig | 13 ++ > > > > drivers/misc/Makefile | 1 + > > > > drivers/misc/gpio-7seg.c | 168 ++++++++++++++++++++ > > > > > > I wonder if it would make sense to merge this into the LED subsystem > > > rather than having it as a standalone driver. > > > > Hum, maybe. How do you see it fitting inside the LED subsystem? The > > purpose of the device is quite different in its userspace to kernel > > interface, no? > > The LED subsystem can be used by both in-kernel and by user space > front-ends. It currently supports on/off, blinking and variable > brightness LEDs. Adding 7-segment LEDs may be a stretch but also > would fit into the same basic interface I think. > > In addition, it would not have to be GPIO based, although that may > be the only implementation we need for the foreseeable future. > Well, unless you make a driver for PC-style "port-0x80" PCI > cards. > > > > > > + sdev->dev_attr.attr.name = "value"; > > > > + sdev->dev_attr.attr.mode = S_IRUGO | S_IWUGO; > > > > + sdev->dev_attr.show = gpio_7seg_show; > > > > + sdev->dev_attr.store = gpio_7seg_store; > > > > > > Any reason why you are not using the DEVICE_ATTR macro? > > > > DEVICE_ATTR declares the structure, and I wanted one per gpio_7seg > > device, which is dynamically allocated, so I thought that using > > DEVICE_ATTR was not possible. But now that you point this, I realize > > that I was stupid. I can perfectly live with one single global 'struct > > device_attribute' that I register to several devices using > > device_create_file(), no? > > Correct. > > > That said, is it worth the effort to continue polishing this driver, > > after seeing the feedback from Greg about it? I don't mind working on > > it more and fix the problems of course, but if the general answer is > > that we don't want such a driver in the kernel, then I'd better not > > spend more time on this. > > I only saw the discussion after I had sent my reply. I think that > this driver in the form of a drivers/misc sysfs driver is not worth > pursuing, but it may still be possible to integrate it nicely into > the LED framework. I also definitely think it should be a kernel driver. This is the sort of low level device useful for debugging that I want available to other kernel modules. g.