From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966618AbcA1O5F (ORCPT ); Thu, 28 Jan 2016 09:57:05 -0500 Received: from bear.ext.ti.com ([192.94.94.41]:37682 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965438AbcA1O5C (ORCPT ); Thu, 28 Jan 2016 09:57:02 -0500 Subject: Re: [PATCH v2] gpio: Add driver for TI TPIC2810 To: Linus Walleij , "linux-leds@vger.kernel.org" , Richard Purdie , Jacek Anaszewski References: <1453738452-23633-1-git-send-email-afd@ti.com> CC: Alexandre Courbot , Javier Martinez Canillas , "linux-gpio@vger.kernel.org" , "linux-kernel@vger.kernel.org" From: "Andrew F. Davis" Message-ID: <56AA2C30.2040708@ti.com> Date: Thu, 28 Jan 2016 08:56:48 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/28/2016 04:47 AM, Linus Walleij wrote: > On Mon, Jan 25, 2016 at 5:14 PM, Andrew F. Davis wrote: > >> Add driver for TI TPIC2810 8-Bit LED Driver with I2C Interface. >> >> The TPIC2810 has 8 open-drain outputs that can but used to drive >> LEDs and other low-side switched resistive loads. >> >> Signed-off-by: Andrew F. Davis >> --- >> Changes from v1: >> - Added OF match table at Javier Martinez Canillas request > > So the TI datasheet says: > "8 bit LED driver with I2C interface" > > So it is *not* "general purpose input/output" (GPIO). > > It is special purpose LED drive output-only circuit. > > So why can it not have a driver directly in drivers/leds/*? > > I understand that it can also be used as a GPIO (and that it > is then nice to put leds-gpio on top of it) but then > I want a reference to the hardware that actually went ahead > and used this as a GPIO chip rather than using a proper > GPIO expander. > > Yours, > Linus Walleij > These don't really have the traditional LED features (current control, HW blinking, etc), and all the use cases I've found treat them as GPO, including our Industrial Dev Kits (although they run them to test LEDs as well as the IO header): http://www.ti.com/tool/tmdsice3359 http://www.ti.com/tool/tmdxidk437x And a couple more that I don't think have any public schematics yet. Like you said, they can still be used for LEDs with leds-gpio, as they don't have any LED specific features I figure this way we get both uses with one driver. Andrew