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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9EECDC28EBB for ; Thu, 6 Jun 2019 11:52:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 70D7B207E0 for ; Thu, 6 Jun 2019 11:52:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="SMis4RP1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727557AbfFFLw3 (ORCPT ); Thu, 6 Jun 2019 07:52:29 -0400 Received: from mail-lf1-f68.google.com ([209.85.167.68]:36881 "EHLO mail-lf1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727110AbfFFLw3 (ORCPT ); Thu, 6 Jun 2019 07:52:29 -0400 Received: by mail-lf1-f68.google.com with SMTP id m15so1325055lfh.4; Thu, 06 Jun 2019 04:52:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=zPLkA/L+MT2tb0YKXYeABZbn8ju7XPPpKF8Cm5YcWwY=; b=SMis4RP11BWLAtEAe/AcVwMHUFdHYhwm4lgqJj0zCFzDFTUR7sVzRouZ3qKXRmUYja paWnrgCl3cj4x8z7kACumI+8hKt8DF/heg1hG78OwcUf+kh8PwF8tq1byYJX08dsJv3X QntZqBkewrE/dYemVY1O7w4uzEcagcyrOvUwZXu8mO0PiIYvDkXzxMFXvQ9M8M/3+tTL YtLrwo1tl9cfMvGORPD/ehP2dTXD5hz5SwwV4dFwNsGbK1ebEq4nRpeMhGzp3OVR7sLU GRlSDfhjgCV53vo1/T5fuYezWkQAgNFknivUQoNm9rzG0kQ/jRPvIPnz6jvjNW+XGsgI ukeg== 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=zPLkA/L+MT2tb0YKXYeABZbn8ju7XPPpKF8Cm5YcWwY=; b=pK9tNXdSLK1mQf0p5OHLhoRf1SCRbl/UaVjeXkZ58rLV+HYrBuxjmlpBJ/KVw1esFp VwSkIZgvzUOTeaBGb5D+p9751jxiqPx/iaT908yi/oqXGHMxV7Ne+ULCI/dS0auRoxHc lQd6zEcyyGxAXIbB0AGwks4ObxhmELFu2JTfRjscYa00V7a0hTtzivzkclCKILCwOJcq Fw9cjzzn/495eS42EbzNcAUSR7cVdHUERuVXz60g6g7JOlU2RBO9rU6uLmi6JKVJ5yx3 cdcDBT6dVSiDOuYnBBn5CKV4MW60wWJgi68lOrCzMDjp8TblMHBvryln9x+mreglvj+n 6CNQ== X-Gm-Message-State: APjAAAWPRLCM8iXqQeOVw4HLaXIhZFcY3XI5SNoEK/t+/Qea9UYy7RGQ 2cW4F41RKVyUHxb2OxfEOuQ= X-Google-Smtp-Source: APXvYqzmyOkZXWN5lfsLPAhrNTYEgiBO+5rUSrFZxFIShj+qXgIAvp9nzbLNM129xeNZKqbYHpi8hw== X-Received: by 2002:ac2:5922:: with SMTP id v2mr23366649lfi.180.1559821946588; Thu, 06 Jun 2019 04:52:26 -0700 (PDT) Received: from [192.168.2.145] ([94.29.35.141]) by smtp.googlemail.com with ESMTPSA id e19sm309810ljj.62.2019.06.06.04.52.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Jun 2019 04:52:25 -0700 (PDT) Subject: Re: [PATCH V1] i2c: busses: tegra: Add suspend-resume support To: Bitan Biswas , Laxman Dewangan , Thierry Reding , Jonathan Hunter , linux-i2c@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Shardar Mohammed , Sowjanya Komatineni , Mantravadi Karthik References: <1559195718-6693-1-git-send-email-bbiswas@nvidia.com> <9142282b-ab76-53a0-13ce-c43b8adc575f@nvidia.com> <4f14a218-332c-0263-c6c5-73a13b2446f0@gmail.com> From: Dmitry Osipenko Message-ID: Date: Thu, 6 Jun 2019 14:52:24 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 06.06.2019 8:43, Bitan Biswas пишет: > > > On 5/31/19 5:43 AM, Dmitry Osipenko wrote: >> 31.05.2019 11:50, Bitan Biswas пишет: >>> >>> >>> On 5/30/19 4:27 AM, Dmitry Osipenko wrote: >>>> 30.05.2019 8:55, Bitan Biswas пишет: >>>>> Post suspend I2C registers have power on reset values. Before any >>>>> transfer initialize I2C registers to prevent I2C transfer timeout >>>>> and implement suspend and resume callbacks needed. Fix below errors >>>>> post suspend: >>>>> >>>>> 1) Tegra I2C transfer timeout during jetson tx2 resume: >>>>> >>>>> [   27.520613] pca953x 1-0074: calling pca953x_resume+0x0/0x1b0 @ >>>>> 2939, parent: i2c-1 >>>>> [   27.633623] tegra-i2c 3160000.i2c: i2c transfer timed out >>>>> [   27.639162] pca953x 1-0074: Unable to sync registers 0x3-0x5. -110 >>>>> [   27.645336] pca953x 1-0074: Failed to sync GPIO dir registers: -110 >>>>> [   27.651596] PM: dpm_run_callback(): pca953x_resume+0x0/0x1b0 >>>>> returns -110 >>>>> [   27.658375] pca953x 1-0074: pca953x_resume+0x0/0x1b0 returned -110 >>>>> after 127152 usecs >>>>> [   27.666194] PM: Device 1-0074 failed to resume: error -110 >>>>> >>>>> 2) Tegra I2C transfer timeout error on jetson Xavier post resume. >>>>> >>>>> Signed-off-by: Bitan Biswas >>>>> --- >>>>>    drivers/i2c/busses/i2c-tegra.c | 24 ++++++++++++++++++++++++ >>>>>    1 file changed, 24 insertions(+) >>>>> >>>>> diff --git a/drivers/i2c/busses/i2c-tegra.c >>>>> b/drivers/i2c/busses/i2c-tegra.c >>>>> index ebaa78d..f6a377f 100644 >>>>> --- a/drivers/i2c/busses/i2c-tegra.c >>>>> +++ b/drivers/i2c/busses/i2c-tegra.c >>>>> @@ -1687,9 +1687,33 @@ static int tegra_i2c_remove(struct >>>>> platform_device *pdev) >>>>>    } >>>>>      #ifdef CONFIG_PM_SLEEP >>>>> +static int tegra_i2c_suspend(struct device *dev) >>>>> +{ >>>>> +    struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev); >>>>> + >>>>> +    i2c_mark_adapter_suspended(&i2c_dev->adapter); >>>>> + >>>>> +    return 0; >>>>> +} >>>>> + >>>>> +static int tegra_i2c_resume(struct device *dev) >>>>> +{ >>>>> +    struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev); >>>>> +    int ret; >>>>> + >>>>> +    i2c_lock_bus(&i2c_dev->adapter, I2C_LOCK_ROOT_ADAPTER); >>>>> +    ret = tegra_i2c_init(i2c_dev, false); >>>>> +    i2c_unlock_bus(&i2c_dev->adapter, I2C_LOCK_ROOT_ADAPTER); >>>> >>>> Why the locking is needed here? >>> >>> async resume could result in stress test issues if some client accesses >>> the i2c instance. This ensures the i2c instance is locked till the >>> initialization is complete. >> >> 1) This doesn't make much sense.. if client could access I2C during of >> tegra_i2c_init execution, then what stops it to perform the access >> before the lock is taken? > Client resumes will start after I2C instance resume because of driver > dependency. Since lock is the first call in i2c-tegra I believe I2C > calls of client will not start. You're incorrectly assuming that client can start resuming in the middle of the controller's resume process. I2C client's resume won't start until tegra_i2c_resume() is finished completely. That is because child drivers are resumed only after theirs parent is ready and this is guaranteed by the drivers core.