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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 C534BC3524A for ; Tue, 4 Feb 2020 03:10:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 90E0F2080D for ; Tue, 4 Feb 2020 03:10:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="g2nWaVqP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727063AbgBDDKa (ORCPT ); Mon, 3 Feb 2020 22:10:30 -0500 Received: from mail-wm1-f68.google.com ([209.85.128.68]:52798 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726930AbgBDDKa (ORCPT ); Mon, 3 Feb 2020 22:10:30 -0500 Received: by mail-wm1-f68.google.com with SMTP id p9so1593209wmc.2 for ; Mon, 03 Feb 2020 19:10:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=yT0IgHPsW5g8ur4OimAHbgZfgffCfBRYN8ASv6hPxKg=; b=g2nWaVqPAYAcEdiBTzCax9T9uYw7qE1Y+YmU7HqWncxCDCQUNJPEuqVFK6+3CTf1x4 2M6YVLcFf4wi1RQAtNMuWibYXZvMixLAIF41b75U1gcQDnQW8XjrsmFONWiKNTVhaOyP cKHQL+3qfreVMQR2JepT5byEmSH5+RULtDOga7kNnxAmYmqPO0Wvl//bJVzd8tDfhrqo AO5z6C/ObQ62bIVb+FVWeCH2tcVxbM9PTJ/25cPTGKbONCUmhaX+UarTmem7MNUFLP4P Ci18lLLTRIsyHDFaw5meXPfsbuAooy6MbU/WlFiWrrd0ssmzLPP8J8swNENJgzRuJhbt IiTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=yT0IgHPsW5g8ur4OimAHbgZfgffCfBRYN8ASv6hPxKg=; b=Hq8ImUO2gNils9d0N0YOmj/WjyNDhAyDNtHjxKvCluEnLheVf8vvuZOdgP1jImQE66 wZrvDqM5tIiyoAa0l2FqKUOiU/MoM8c/8HNlLelSqSAqTi5Cof02Vxexlj176I+gPLqQ DJAf1rkpqV1Lj/b4pPnnKAKrA8V9IW5AxLH0ILZgB+XX3YgG1S2kDEd76nBXA6aoytPG x8Tze08JMMO2ouGlptFphkZzniTcGHpl5y1aV7/NwKjX2QA6TBl6TkqDgy9u9zyD1YRF s5oTsP0q4dJxwZc8IGsMAT6ungY9XCy0rJlGmw4c8xaWPXyGoxd77SbrfWqySgiEfqXC q2Qg== X-Gm-Message-State: APjAAAXg2iWaDTLpiTCTjC9TOVXDZ8PvZOHxPQwBsar+ASw7o59kOZ8C NvvJeADQ+X4axrzO4keauxXI4A== X-Google-Smtp-Source: APXvYqwy3uFhqzHsHZsT0Oi406B8+nMO5cCRUWUlW0U7SYrZreocKAM0+mv9L6fc4kzkRSsZNNI4ag== X-Received: by 2002:a7b:ce84:: with SMTP id q4mr2428082wmj.57.1580785827826; Mon, 03 Feb 2020 19:10:27 -0800 (PST) Received: from [192.168.0.38] ([176.61.57.127]) by smtp.gmail.com with ESMTPSA id z3sm11018098wrs.32.2020.02.03.19.10.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Feb 2020 19:10:27 -0800 (PST) Subject: Re: [PATCH v4 2/2] Embedded USB Debugger (EUD) driver To: Bjorn Andersson , Avaneesh Kumar Dwivedi Cc: linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, ckadabi@codeaurora.org, tsoni@codeaurora.org, bryanh@codeaurora.org, psodagud@codeaurora.org, rnayak@codeaurora.org, satyap@codeaurora.org, pheragu@codeaurora.org References: <1580445811-15948-1-git-send-email-akdwived@codeaurora.org> <1580445811-15948-3-git-send-email-akdwived@codeaurora.org> <20200203193533.GL3948@builder> From: Bryan O'Donoghue Message-ID: <5008a446-a90c-b68a-aaa4-3e7cd90418fa@linaro.org> Date: Tue, 4 Feb 2020 03:10:30 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <20200203193533.GL3948@builder> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On 03/02/2020 19:35, Bjorn Andersson wrote: > On Thu 30 Jan 20:43 PST 2020, Avaneesh Kumar Dwivedi wrote: Hi Avaneesh. > Please aim for keeping the sort order in this file (ignore QCOM_APR > which obviously is in the wrong place) > >> + tristate "QTI Embedded USB Debugger (EUD)" >> + depends on ARCH_QCOM If we persist with the model of EXTCON you should "select EXTCON" here. >> + help >> + The Embedded USB Debugger (EUD) driver is a driver for the >> + control peripheral which waits on events like USB attach/detach >> + and charger enable/disable. The control peripheral further helps >> + support the USB-based debug and trace capabilities. >> + This module enables support for Qualcomm Technologies, Inc. >> + Embedded USB Debugger (EUD). Suggest. This module enables support for Qualcomm Technologies, Inc. Embedded USB Debugger (EUD). The EUD is a control peripheral which reports VBUS attach/detach, charger enable/disable and USB-based debug and trace capabilities. >> + * Copyright (c) 2016-2018, The Linux Foundation. All rights reserved. 2020 >> + >> +static int enable_eud(struct eud_chip *priv) >> +{ >> + int ret; >> + >> + /* write into CSR to enable EUD */ >> + writel_relaxed(BIT(0), priv->eud_reg_base + EUD_REG_CSR_EUD_EN); >> + /* Enable vbus, chgr & safe mode warning interrupts */ >> + writel_relaxed(EUD_INT_VBUS | EUD_INT_CHGR | EUD_INT_SAFE_MODE, >> + priv->eud_reg_base + EUD_REG_INT1_EN_MASK); >> + >> + /* Ensure Register Writes Complete */ So... You are writing a register in an on-chip PMIC. The PMIC is responsible for detecting USB ID and supplying VBUS as appropriate. You then get an interrupt to inform you of the state ? >> +static ssize_t enable_store(struct device *dev, >> + struct device_attribute *attr, >> + const char *buf, size_t count) >> +{ >> + struct eud_chip *chip = dev_get_drvdata(dev); >> + int enable = 0; > > You shouldn't need to initialize this as you're checking the return > value of sscanf(). > >> + int ret = 0; >> + >> + if (sscanf(buf, "%du", &enable) != 1) >> + return -EINVAL; >> + >> + if (enable == EUD_ENABLE_CMD) >> + ret = enable_eud(chip); > > If ret is !0 you should probably return that, rather than count... > >> + else if (enable == EUD_DISABLE_CMD) >> + disable_eud(chip); >> + if (!ret) > > ...and then you don't need this check, or initialize ret to 0 above. > >> + chip->enable = enable; > > So if I write 42 to "enable" nothing will change in the hardware, but > chip->enable will be 42... > >> + return count; >> +} I was just going to comment on usb_connector but, does the above code need a synchronization primitive to serialize with the worker and interrupt handler ? >> +static int msm_eud_probe(struct platform_device *pdev) >> +{ >> + struct eud_chip *chip; >> + struct resource *res; >> + int ret; >> + >> + chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL); >> + if (!chip) >> + return -ENOMEM; >> + >> + chip->dev = &pdev->dev; >> + platform_set_drvdata(pdev, chip); >> + >> + chip->extcon = devm_extcon_dev_allocate(&pdev->dev, eud_extcon_cable); > > Aren't we moving away from extcon in favor of the usb role switching > thing? Yes. For the VBUS notification you could use usb-role-switch and model the USB connector as a child-node of the dual-role controller. See: https://patchwork.kernel.org/cover/11346247/ https://patchwork.kernel.org/patch/11346295/ https://patchwork.kernel.org/patch/11346263/ Avaneesh do you have any kernel code that cares about the charger state ? What we are suggesting here is dropping extcon and using role-switching but, if you have some other code that cares about EXTCON_CHG_USB_SDP you'd have to do additional work. But, if I understood the implication of the code above where you write to the PMIC and let it handle VBUS/CHARGER on/off and you are just notified of the state change, you should be fine with usb-role-switching. --- bod