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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06BEEC77B73 for ; Tue, 2 May 2023 10:19:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233808AbjEBKTh (ORCPT ); Tue, 2 May 2023 06:19:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233657AbjEBKTM (ORCPT ); Tue, 2 May 2023 06:19:12 -0400 Received: from mail-ed1-x52d.google.com (mail-ed1-x52d.google.com [IPv6:2a00:1450:4864:20::52d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC70E5597 for ; Tue, 2 May 2023 03:19:10 -0700 (PDT) Received: by mail-ed1-x52d.google.com with SMTP id 4fb4d7f45d1cf-50bcc565280so1901834a12.2 for ; Tue, 02 May 2023 03:19:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1683022749; x=1685614749; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=PSOQWv5cIhWugBKgY0Tf8haO/+bAiIBjy0ljcFCS7pE=; b=sU4YH9jOZeGVjyZ1m4F/RektzfkMf2vg9+4cIdsuJaEOX/tAdSZjMllV324DlTO4is 3BVDhUi3OnaY5mVCoDnuClb/yZ+UXhfMtl8Hw0Hw9LRhwxvcVWx/Jgu+DHUxr/rxFIo6 j38ucgy3ttImNwyrLZzyaSQv2VPW7ugbSoaw+zAleDh1lepsNQXyENSYJXEvDzQ9r2xi Ra7ptpkuNvOZjqkh7EH5yboRJ/5veLuJr2nOB98dSWOpxlWjrPctyxwgoBj3l+ytl4jn HvAOE5WdLxZECWEO4aoKxzZivNqaP+6P3way5gkg5/pL9AfdZz1nRqNLYwpKrZbDtbbh BnQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1683022749; x=1685614749; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=PSOQWv5cIhWugBKgY0Tf8haO/+bAiIBjy0ljcFCS7pE=; b=Cwqga4KvgRcUDRVI/yFvuNJ+cST7ZR/e4KcokOFuRUiSfljuypabjtSUTiAB0NGxPY SkQRTSZdXYxAB7626u00aDl8QaYy+zBVjwNMZzSOBeGGA541eEo3mDu8DMOXDHOyl1iF 1bp4Ingi4dOk8jccuEVr1719NRLC91px9EL+VhPIhNMXIEK2benNR2DTRWi8fxOcCL2m IlE3eGyJb84KP3KU8/3geI0wQ7EUQOM3TpMbJ+jwjS0t33S0/62ruRzC0ZBnyGRdfg0W XG40dcc6xbsKHY8Q+o21CT4VUbGMciGxe5nleGeQXenaKE0lkGDFVwffpMoO9WQhIAdg nYDg== X-Gm-Message-State: AC+VfDzMo56g3FR0Nc35o2xZInfCdUy/bVFQiXwo00+m1wcHFMnKlcQK LFkMhVx4CP/LTRqJc55/N1eGbA== X-Google-Smtp-Source: ACHHUZ7tLdRIYdOi6QjvP8Fn9gC7J1+rSZR+Ue+G/TFVdN8qdNoXM1jyPVQaYKSzGHlTX9Pdknpw7Q== X-Received: by 2002:a05:6402:8:b0:504:8c1a:70db with SMTP id d8-20020a056402000800b005048c1a70dbmr7705427edu.32.1683022749367; Tue, 02 May 2023 03:19:09 -0700 (PDT) Received: from ?IPV6:2a02:810d:15c0:828:bafd:1283:b136:5f6a? ([2a02:810d:15c0:828:bafd:1283:b136:5f6a]) by smtp.gmail.com with ESMTPSA id u10-20020a056402064a00b00506addaaab0sm13225333edx.32.2023.05.02.03.19.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 02 May 2023 03:19:08 -0700 (PDT) Message-ID: <59b9214a-19e6-fd4e-6982-6e8c28c7e4a8@linaro.org> Date: Tue, 2 May 2023 12:19:07 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [PATCH 1/2] dt-bindings: Add optional gpio property to uartps node to support rs485 Content-Language: en-US To: "Guntupalli, Manikanta" , Rob Herring Cc: "gregkh@linuxfoundation.org" , "krzysztof.kozlowski+dt@linaro.org" , "michal.simek@xilinx.com" , "linux-serial@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "jirislaby@kernel.org" , "linux-arm-kernel@lists.infradead.org" , "Simek, Michal" , "git (AMD-Xilinx)" , "Pandey, Radhey Shyam" , "Datta, Shubhrajyoti" , "Goud, Srinivas" , "manion05gk@gmail.com" References: <1682512187-8828-1-git-send-email-manikanta.guntupalli@amd.com> <1682512187-8828-2-git-send-email-manikanta.guntupalli@amd.com> <20230427164351.GA3146210-robh@kernel.org> From: Krzysztof Kozlowski In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/05/2023 12:14, Guntupalli, Manikanta wrote: > Hi Rob Herring, > >> -----Original Message----- >> From: Rob Herring >> Sent: Thursday, April 27, 2023 10:14 PM >> To: Guntupalli, Manikanta >> Cc: gregkh@linuxfoundation.org; krzysztof.kozlowski+dt@linaro.org; >> michal.simek@xilinx.com; linux-serial@vger.kernel.org; >> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; >> jirislaby@kernel.org; linux-arm-kernel@lists.infradead.org; Simek, Michal >> ; git (AMD-Xilinx) ; Pandey, >> Radhey Shyam ; Datta, Shubhrajyoti >> ; Goud, Srinivas ; >> manion05gk@gmail.com >> Subject: Re: [PATCH 1/2] dt-bindings: Add optional gpio property to uartps >> node to support rs485 >> >> On Wed, Apr 26, 2023 at 05:59:46PM +0530, Manikanta Guntupalli wrote: >>> Add optional gpio property to uartps node and add reference to rs485.yaml >> >> The diff tells me that already. Why? > Please check Figure 11-3 (Page number 37) in the below mentioned data sheet, It shows PMOD (ISOW14x2) devices used in half duplex configuration. Driver outputs Y and Z are shorted to A and B respectively. This reduces overall cabling requirements. Also DE/RE are shorted to each other, and at a time, any node acts as either a driver or a receiver. > Using above optional GPIO controlling driver or a receiver. This GPIO is optional because it is not required for uart console node. > > Here, > DE - Driver enable. If pin is floating, driver is disabled (internal pull-down resistor) > RE - Receiver enable. If pin is floating, receiver buffer is disabled (internal pull-up resistor) > > Datasheet: > https://www.ti.com/lit/ds/symlink/isow1432.pdf?ts=1682607122706&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FISOW1432%252Fpart-details%252FISOW1432DFMR%253FkeyMatch%253DISOW1432DFMR%2526tisearch%253Dsearch-everything%2526usecase%253DOPN Your request for us to get into some datasheet somewhere, to get the answer to the basic question, is not reasonable. Commit must justify its existence, not some external source. > >> >>> >>> Signed-off-by: Manikanta Guntupalli >>> --- >>> Documentation/devicetree/bindings/serial/cdns,uart.yaml | 5 +++++ >>> 1 file changed, 5 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/serial/cdns,uart.yaml >> b/Documentation/devicetree/bindings/serial/cdns,uart.yaml >>> index a8b323d7bf94..34ed0d80b923 100644 >>> --- a/Documentation/devicetree/bindings/serial/cdns,uart.yaml >>> +++ b/Documentation/devicetree/bindings/serial/cdns,uart.yaml >>> @@ -46,6 +46,10 @@ properties: >>> power-domains: >>> maxItems: 1 >>> >>> + txrx-gpios: >>> + description: Optional GPIO to switch transmit and receive modes via >> pmod. >> >> What's pmod? > Pmod is galvanically-isolated RS-485/RS-422 transceivers with a built-in isolated > DC-DC converter, that eliminates the need for a separate isolated power supply in > space constrained isolated designs. It's not about explaining it here, but making your changes justified and obvious once implemented. Best regards, Krzysztof