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=-1.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 A0F99C43381 for ; Mon, 25 Mar 2019 09:44:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 710522087F for ; Mon, 25 Mar 2019 09:44:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=baylibre-com.20150623.gappssmtp.com header.i=@baylibre-com.20150623.gappssmtp.com header.b="yoa2l5HT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730778AbfCYJoI (ORCPT ); Mon, 25 Mar 2019 05:44:08 -0400 Received: from mail-wm1-f66.google.com ([209.85.128.66]:53949 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730750AbfCYJoF (ORCPT ); Mon, 25 Mar 2019 05:44:05 -0400 Received: by mail-wm1-f66.google.com with SMTP id q16so8107786wmj.3 for ; Mon, 25 Mar 2019 02:44:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20150623.gappssmtp.com; s=20150623; h=message-id:subject:from:to:cc:date:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=sjUvDw4gOuiKbCS9+L4oee/43lzsOILkxD3UaEvPcUw=; b=yoa2l5HTCJDO4Qd6U5rUO2b4WmP82IkULUq78oxV7j/Ax1s1hLAsn8c1aJ570M4LLC N05lcoIrTthH4x6l9yXaX3y8KcXf/H5LGSmkAppOeqM6d0RxPt/axfNLiGF7Vsa/TgIC 5/bKzMF+gYcPKSITZqN4iauYfCWOvsEadumgTNxXuh8cCWpPB3TOufiia3tnHEZ8S0PP 6sPftosrlPemduitr4nVbZIR6RTahp4w0I3DE/Z2oQ5C2/77UsmrlsPg2ggjlp0eNPYX emd6NH9e0Guu9+ePoTOI2kpmNWrzlv18QalAijZKo9Kamt8v9o8Wqzc7mR3bSXJ+R7OL BDkg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=sjUvDw4gOuiKbCS9+L4oee/43lzsOILkxD3UaEvPcUw=; b=U6E9s87TYSqgEeN1UZsrM3sF0I2JZbi5SwWIA5Pl3vYB6nW9vjC2cFHZ7wsziDCZHW MZFs3Jux4e+e8r+3pdgB6UMx3o8LfupdrsVHMw1YW2KlZhbc/1EuK9CNhGKTUtz13W9b 2rbB0+qigkYII1s/bhILaqOcWgQM9HEzW5MmgqVKTKyg9UoDw46kGJ6gmOK+tiR8WdU4 lXKddCWU3OyBNUaCdWkkHVeDbqW24w+It8jW1UX0ePUDx746hicQe/uwt0moMtIOd1YU T/GmL+F46V4Pgxco7CAW5RMrLdRXh7VFwFCbZHQl67kG+KvNlXWfrUiR+kQZfyn070qb 3NZg== X-Gm-Message-State: APjAAAXZWy16ruXefEppwXihmkvA7nhhDXV2+2Rbz3nSuSIWa0Hm2qaE S019coG/bvkVK1ZR5Y9z3zwsRw== X-Google-Smtp-Source: APXvYqxgrEbmaJqb5t5YUHDJ+RSVQ8fPlX7fZ6D13OQumRAB3s5mmhRsLE0YzZ9FidXQfGQOu7FCeg== X-Received: by 2002:a1c:480b:: with SMTP id v11mr9792761wma.25.1553507043298; Mon, 25 Mar 2019 02:44:03 -0700 (PDT) Received: from boomer.baylibre.com ([2a01:e34:eeb6:4690:106b:bae3:31ed:7561]) by smtp.gmail.com with ESMTPSA id h9sm3591056wmb.5.2019.03.25.02.44.01 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 25 Mar 2019 02:44:02 -0700 (PDT) Message-ID: <283b286671a65160ac8ae08b1e1889bc029db363.camel@baylibre.com> Subject: Re: [PATCH 0/2] pinctrl: meson: add g12a drive strength support From: Jerome Brunet To: Linus Walleij , Kevin Hilman , =?UTF-8?Q?Go=C5=82aszewski=2C?= Bartosz , Kevin Hilman Cc: devicetree@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, Guillaume La Roque Date: Mon, 25 Mar 2019 10:44:00 +0100 In-Reply-To: <20190314163725.7918-1-jbrunet@baylibre.com> References: <20190314163725.7918-1-jbrunet@baylibre.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2019-03-14 at 17:37 +0100, Jerome Brunet wrote: > The purpose of this patchset is to add drive-strength support in meson pinconf > driver. This is a new feature that was added on the g12a. It is critical for us > to support this since many functions are failing with default pad drive-strength. > > Now the slightly annoying part :( > The value achievable by the SoC are 0.5mA, 2.5mA, 3mA and 4mA and the DT property > 'drive-strength' is expressed in mA. > > 1) Rounding down the value, we could be requesting a 0mA drive strength. > That would look weird. > 2) Rounding up, we can't distinguish between 2.5mA and 3mA > > To solve this issue in this in this v1, we chose to document that, on Amlogic, > drive-strength is expressed in uA instead of mA. > It works well and there is no impact on the other platforms but I'm not sure this > is really OK with the DT rules ? > > Linus, if this is not OK with you, here are 2 other options we are > considering. We would be very interested to get your opinion on the matter: > > 1) instead the generic 'drive-strength' property, we could add an amlogic > specific property, 'amlogic,drive-strength'. It would be expressed in uA > and parsed in amlogic specific code. > I think this option is kind of overkill. Expressing drive strength in uA is > not really amlogic specific so it does not make much sense, but it would > work ... > > 2) Add another generic property "drive-strength-uA". The change to do so > would be minimal and could be benefit to other platforms later on. Hi Linus, I know it has only been 10 days and you must be busy but I was wondering if we could get your view on the issue above ? Since the vast majority of SoC functions need a drive strength setting, DT patches are somehow blocked until we decide which binding to use for it. Sorry for this early ping. Jerome > > Cheers > Jerome > > Guillaume La Roque (2): > dt-bindings: pinctrl: meson: Add drive-strength property > pinctrl: meson: add support of drive-strength > > .../bindings/pinctrl/meson,pinctrl.txt | 3 + > drivers/pinctrl/meson/pinctrl-meson-g12a.c | 36 ++-- > drivers/pinctrl/meson/pinctrl-meson.c | 166 +++++++++++++----- > drivers/pinctrl/meson/pinctrl-meson.h | 20 ++- > 4 files changed, 165 insertions(+), 60 deletions(-) >