From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E9DABC47085 for ; Mon, 24 May 2021 16:05:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D1B466109F for ; Mon, 24 May 2021 16:05:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236216AbhEXQGj (ORCPT ); Mon, 24 May 2021 12:06:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237258AbhEXQFP (ORCPT ); Mon, 24 May 2021 12:05:15 -0400 Received: from polaris.svanheule.net (polaris.svanheule.net [IPv6:2a00:c98:2060:a004:1::200]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58438C08C5DE for ; Mon, 24 May 2021 08:20:16 -0700 (PDT) Received: from [IPv6:2a02:a03f:eafb:ee01:cbcc:e481:3e58:4db1] (unknown [IPv6:2a02:a03f:eafb:ee01:cbcc:e481:3e58:4db1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: sander@svanheule.net) by polaris.svanheule.net (Postfix) with ESMTPSA id AACCD202FE2; Mon, 24 May 2021 17:20:14 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=svanheule.net; s=mail1707; t=1621869615; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KKLQc2NBPOHNUHuTQ5VD+lESnzXxzbFhPv9iqnAedX0=; b=U8O/lCMbraND+fUwsMSmNU7BX7DyIgkOE5GmzcAlF+BsqPEh5+xyarQ9QMacOZXRoUsHdj cWTjPBxmX3lJ6iQXrr/Nxyc1PdPbTAcHuH0adEgDbUcasGzEH+cqBYlXK/5Kt8dX8AsCGF MNzJQqP2eKTWUP2vzwEEVraU0z8SjvOZFhbPNBeS4MXm9OexdrCyyl3EQ73V3USNvvsl9p LY9NwbZSOCEvxEFsjtFxbL69B3FmdOvuz9GdJFMOng/e9NcRN4nmBzhrInTfkPddOG6EtI hznHNDLlmof6dPNvyPl8+pjVC9LivmOuvhzOGR3RmS8ZJxDBkwfUW4PHLvsiTw== Message-ID: <69c95adb6bafb8fbf69b9f79613606f62ba769e8.camel@svanheule.net> Subject: Re: [PATCH v3 0/6] RTL8231 GPIO expander support From: Sander Vanheule To: Andy Shevchenko Cc: Andrew Lunn , Pavel Machek , Rob Herring , Lee Jones , Mark Brown , Greg Kroah-Hartman , "Rafael J . Wysocki" , Michael Walle , Linus Walleij , Bartosz Golaszewski , Linux LED Subsystem , devicetree , "open list:GPIO SUBSYSTEM" , Linux Kernel Mailing List Date: Mon, 24 May 2021 17:20:13 +0200 In-Reply-To: References: <02bbf73ea8a14119247f07a677993aad2f45b088.camel@svanheule.net> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.4 (3.38.4-1.fc33) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org Hi Andy, Forgot to reply to the sysfs suggestion. On Mon, 2021-05-24 at 15:54 +0300, Andy Shevchenko wrote: > On Mon, May 24, 2021 at 2:41 PM Sander Vanheule wrote: > > On Mon, 2021-05-24 at 10:53 +0300, Andy Shevchenko wrote: > > > On Mon, May 24, 2021 at 4:11 AM Andrew Lunn wrote: > > > > > >   - Introduce GPIO regmap quirks to set output direction first > > > > > > > > I thought you had determined it was possible to set output before > > > > direction? > > > > > > Same thoughts when I saw an updated version of that patch. My > > > anticipation was to not see it at all. > > > > The two devices I've been trying to test the behaviour on are: > >  * Netgear GS110TPP: has an RTL8231 with three LEDs, each driven via a pin > >    configured as (active-low) GPIO. The LEDs are easy for a quick visual > > check. > >  * Zyxel GS1900-8: RTL8231 used for the front panel button, and an active- > > low > >    GPIO used to hard reset the main SoC (an RTL8380). I've modified this > > board > >    to change some of the strapping pin values, but testing with the jumpers > > and > >    pull-up/down resistors is a bit more tedious. > > > > On the Netgear, I tested the following with and without the quirk: > > > >    # Set as OUT-LOW twice, to avoid the quirk. Always turns the LED on > >    gpioset 1 32=0; gpioset 1 32=0 > >    # Get value to change to input, turns the LED off (high impedance) > >    # Will return 1 due to (weak) internal pull-up > >    gpioget 1 32 > >    # Set as OUT-HIGH, should result in LED off > >    # When the quirk is disabled, the LED turns on (i.e. old OUT-LOW value) > >    # When the quirk is enabled, the LED remains off (i.e. correct OUT-HIGH > > value) > >    gpioset 1 32=1 > > > > Now, what's confusing (to me) is that the inverse doesn't depend on the > > quirk: > > > >    # Set as OUT-HIGH twice > >    gpioset 1 32=1; gpioset 1 32=1 > >    # Change to high-Z > >    gpioget 1 32 > >    # Set to OUT-LOW, always results in LED on, with or without quirk > >    gpioset 1 32=0 > > > > Any idea why this would be (or appear) broken on the former case, but not on > > the > > latter? > > GPIO tools for the shell are context-less. Can you reproduce this with > the legacy sysfs interface? Using the sysfs interface produced the same behaviour for both test cases. E.g. case 1: # Set to output low echo out > direction; echo 0 > value # Change to input (with weak pull-up) echo in > direction # Try to set to output high # Fails to go high if the pin value is set before the direction echo high > direction Best, Sander