From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751704AbdJWTNU (ORCPT ); Mon, 23 Oct 2017 15:13:20 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:52687 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751429AbdJWTNS (ORCPT ); Mon, 23 Oct 2017 15:13:18 -0400 X-Google-Smtp-Source: ABhQp+SeC7IGmuFNQMeUNFetltJKDjzj4P9vn3s4XLmflg1B15HRkM0t3oN7oBr0CLb6RthSdE8B7w== Subject: Re: about pca955x led driver gpio management To: =?UTF-8?Q?C=c3=a9dric_Le_Goater?= References: <998d7654-f69a-1a99-d4e7-19abd0a54da0@kaod.org> <4ac527f2-c59e-70a2-efd4-da52370ea557@dave.eu> Cc: Andrea Scian - DAVE Embedded Systems , Bryan Wu , Richard Purdie , Jacek Anaszewski , linux-leds@vger.kernel.org, linux-kernel From: Jacek Anaszewski X-Enigmail-Draft-Status: N1110 Message-ID: <9fc08465-db1e-66d4-d07e-f7a9b45add4f@gmail.com> Date: Mon, 23 Oct 2017 21:12:22 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <4ac527f2-c59e-70a2-efd4-da52370ea557@dave.eu> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Cedric, Andrea seems to come across a real issue. We might proceed with the contribution of his patch without your review and possibly Tested-by, but it would be nevertheless beneficial if we had them. Best regards, Jacek Anaszewski On 10/17/2017 11:16 AM, Andrea Scian - DAVE Embedded Systems wrote: > >> On 10/17/2017 10:20 AM, Andrea Scian - DAVE Embedded Systems wrote: >>> >>> Il 17/10/2017 10:18, Cédric Le Goater ha scritto: >>>> On 10/17/2017 09:36 AM, Andrea Scian - DAVE Embedded Systems wrote: >>>>> Dear all, >>>>> >>>>> I'm working on an iMX6 based board with a PCA9555 which is used >>>>> both to drive LEDs and manage some GPIOs. >>>> The PCA9555 chip and the PCA955[0-3] chips have different control >>>> registers. You need a different led driver for it. >>> >>> My typo sorry, as you can see in the device tree below, I'm using >>> pca9551 >> >> ok. >> >> You might want to take a look at how we mixed gpios and leds on the >> witherspoon >> system using pca9552 chips. we added a gpio-leds binding. >> >> https://github.com/openbmc/linux/blob/dev-4.10/arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts >> > > understood: you configure all pins of PCA955x as GPIOs and the map the > one you need as led with gpio-leds binding. > > However to me this is a kind of workaround or, at least, there's nothing > about this limitation into the devicetree binding (in fact, IMHO, the > device tree binding example will just fail) > > I wrote the attached patch which should fix the issue and allow a more > generic approach. WDYT? > > (in case it looks good, I'll send the patch in the correct way) > > > Kind Regards, > > Andrea > >>> >>>>> My current kernel is quite old (4.1.15) but I've found Cédric >>>>> patches on mainline and backported to this old revision. >>>>> >>>>> I'm facing an issue with it, because it seems that it fails when >>>>> it's used in a mixed (led/gpios) environment. >>>>> >>>>> E.g.: let's say that I have one led connected to LED0 output and >>>>> one GPIO connected at LED1 output. >>>>> >>>>> I define it as >>>>> >>>>> pca9551: pca9551@60 { >>>>> compatible = "nxp,pca9551"; >>>>> reg = <0x60>; >>>>> #address-cells = <1>; >>>>> #size-cells = <0>; >>>>> #gpio-cells = <1>; >>>>> >>>>> led@0 { >>>>> label = "led0"; >>>>> reg = <0>; >>>>> linux,default-trigger = >>>>> "none"; >>>>> }; >>>>> gpio@1 { >>>>> label = "gpio1"; >>>>> reg = <1>; >>>>> type = <2>; /* GPIO */ >>>>> }; >>>>> }; >>>>> >>>>> At boot it's probed as >>>>> >>>>> root@sbc-lynx:~# dmesg | grep pca >>>>> [ 5.315425] leds-pca955x 5-0060: leds-pca955x: Using pca9551 >>>>> 8-bit LED driver at slave address 0x60 >>>>> [ 5.350349] leds-pca955x 5-0060: gpios 511...511 >>>>> >>>>> But I cannot access it: >>>>> >>>>> root@sbc-lynx:~# echo 511 > /sys/class/gpio/export >>>>> -sh: echo: write error: Device or resource busy >>>>> >>>>> Because for pca955x_gpio_request_pin() this is at offset 0 (in fact >>>>> is the first gpio registered of this gpio_chip) but it's the index >>>>> 1 inside pca955x->leds[] >>>>> >>>>> Am I missing something? (maybe I made a mistake in my backport >>>>> and/or I'm missing some patches about the GPIO subsystems). >>>>> >>>>> If I'm right I think I can send a patch to fix this (I'm thinking >>>>> about having an array of GPIO index to map offset -> >>>>> pca955x->leds[] index or just register all pins as GPIOs and then >>>>> just report the busy state) >>>>> >>>>> WDYT? >>>>> >>>>> Kind Regards, >>>>> >>> >>