From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bitan Biswas Subject: Re: [PATCH V1] i2c: busses: tegra: Add suspend-resume support Date: Wed, 5 Jun 2019 22:43:36 -0700 Message-ID: References: <1559195718-6693-1-git-send-email-bbiswas@nvidia.com> <9142282b-ab76-53a0-13ce-c43b8adc575f@nvidia.com> <4f14a218-332c-0263-c6c5-73a13b2446f0@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <4f14a218-332c-0263-c6c5-73a13b2446f0@gmail.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Dmitry Osipenko , 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 List-Id: linux-tegra@vger.kernel.org On 5/31/19 5:43 AM, Dmitry Osipenko wrote: > 31.05.2019 11:50, Bitan Biswas =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> >> >> On 5/30/19 4:27 AM, Dmitry Osipenko wrote: >>> 30.05.2019 8:55, Bitan Biswas =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>> 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: >>>> >>>> [=C2=A0=C2=A0 27.520613] pca953x 1-0074: calling pca953x_resume+0x0/0x= 1b0 @ >>>> 2939, parent: i2c-1 >>>> [=C2=A0=C2=A0 27.633623] tegra-i2c 3160000.i2c: i2c transfer timed out >>>> [=C2=A0=C2=A0 27.639162] pca953x 1-0074: Unable to sync registers 0x3-= 0x5. -110 >>>> [=C2=A0=C2=A0 27.645336] pca953x 1-0074: Failed to sync GPIO dir regis= ters: -110 >>>> [=C2=A0=C2=A0 27.651596] PM: dpm_run_callback(): pca953x_resume+0x0/0x= 1b0 >>>> returns -110 >>>> [=C2=A0=C2=A0 27.658375] pca953x 1-0074: pca953x_resume+0x0/0x1b0 retu= rned -110 >>>> after 127152 usecs >>>> [=C2=A0=C2=A0 27.666194] PM: Device 1-0074 failed to resume: error -11= 0 >>>> >>>> 2) Tegra I2C transfer timeout error on jetson Xavier post resume. >>>> >>>> Signed-off-by: Bitan Biswas >>>> --- >>>> =C2=A0 drivers/i2c/busses/i2c-tegra.c | 24 ++++++++++++++++++++++++ >>>> =C2=A0 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) >>>> =C2=A0 } >>>> =C2=A0 =C2=A0 #ifdef CONFIG_PM_SLEEP >>>> +static int tegra_i2c_suspend(struct device *dev) >>>> +{ >>>> +=C2=A0=C2=A0=C2=A0 struct tegra_i2c_dev *i2c_dev =3D dev_get_drvdata(= dev); >>>> + >>>> +=C2=A0=C2=A0=C2=A0 i2c_mark_adapter_suspended(&i2c_dev->adapter); >>>> + >>>> +=C2=A0=C2=A0=C2=A0 return 0; >>>> +} >>>> + >>>> +static int tegra_i2c_resume(struct device *dev) >>>> +{ >>>> +=C2=A0=C2=A0=C2=A0 struct tegra_i2c_dev *i2c_dev =3D dev_get_drvdata(= dev); >>>> +=C2=A0=C2=A0=C2=A0 int ret; >>>> + >>>> +=C2=A0=C2=A0=C2=A0 i2c_lock_bus(&i2c_dev->adapter, I2C_LOCK_ROOT_ADAP= TER); >>>> +=C2=A0=C2=A0=C2=A0 ret =3D tegra_i2c_init(i2c_dev, false); >>>> +=C2=A0=C2=A0=C2=A0 i2c_unlock_bus(&i2c_dev->adapter, I2C_LOCK_ROOT_AD= APTER); >>> >>> 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. >=20 > 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=20 dependency. Since lock is the first call in i2c-tegra I believe I2C=20 calls of client will not start. >=20 > 2) The whole point of the i2c_mark_adapter_* API is to catch those > faulty clients that have a broken suspend-resume sequence. Client will > get a -ESHUTDOWN on trying to issue I2C transfer while controller is > marked as suspended. i2c lock bus calls were used in the resume callback implementation that=20 was reverted few months back. Hence, these were added in this patch=20 which should be more like a revert-of-revert . But I feel probably your point also makes sense. Old resume callback did=20 not have i2c_mark_adapter_* calls. Based on the i2c_adapter_mark_* API=20 documentation it should be taking care that core i2c calls from client=20 are not started. I plan to update the patch and remove the lock-unlock=20 guards in resume callback. >=20 > 3) Please don't use async suspend-resume where it doesn't make sense. This is a system wide setting. /sys/power/pm_async by default is 1 and=20 there is no driver specific change in this patch to choose async=20 suspend-resume. >=20 > Corollary: you should drop the locking because it doesn't do anything > useful. >=20 I did some basic suspend resume tests and do not see any problems=20 removing the i2c_lock_bus call you pointed out. -Thanks, Bitan 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,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH,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 ACE06C04AB5 for ; Thu, 6 Jun 2019 05:43:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7617A20872 for ; Thu, 6 Jun 2019 05:43:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="gYqqAHLr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726567AbfFFFno (ORCPT ); Thu, 6 Jun 2019 01:43:44 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:14040 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725782AbfFFFno (ORCPT ); Thu, 6 Jun 2019 01:43:44 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 05 Jun 2019 22:43:41 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Wed, 05 Jun 2019 22:43:42 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Wed, 05 Jun 2019 22:43:42 -0700 Received: from [10.19.65.14] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 6 Jun 2019 05:43:39 +0000 Subject: Re: [PATCH V1] i2c: busses: tegra: Add suspend-resume support To: Dmitry Osipenko , Laxman Dewangan , Thierry Reding , Jonathan Hunter , , , 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: Bitan Biswas Message-ID: Date: Wed, 5 Jun 2019 22:43:36 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <4f14a218-332c-0263-c6c5-73a13b2446f0@gmail.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1559799821; bh=GE4p/vNNji/ezHHwZOaHDuH9S3e2H9hCagygywOKcME=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=gYqqAHLrmwQ5AEHYn1VMWyqe+igo0+6oE4x0eX43U88GDpI1+wRnq+DFvBMOceaFO lFvLPjv7qgng5rb8JZdByXhDvHcEr1jMbGIyYKNYUjfAtGjPC7KPFQIzyVgXkcMkp7 PmEPTd4JbRacOsHdNC/EfsiLG4Zz4NuJjWhxSz1KtXk8VGRFg4eo7AGwEuFEAO65s6 KH+w7DxWR/yOZ1Y0j14jvyNS91zpf5shU8SvtNzxbATvOgpfGJLAA7GrBGzCCQ8dGD b+iQpz4sLueC9HJ1UVLFfeHHQ5FvSD2seERCpM4hvCFdQfu1YRHVGIdEPbxOYSwSCv LvzNnTi13Txfw== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/31/19 5:43 AM, Dmitry Osipenko wrote: > 31.05.2019 11:50, Bitan Biswas =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> >> >> On 5/30/19 4:27 AM, Dmitry Osipenko wrote: >>> 30.05.2019 8:55, Bitan Biswas =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>> 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: >>>> >>>> [=C2=A0=C2=A0 27.520613] pca953x 1-0074: calling pca953x_resume+0x0/0x= 1b0 @ >>>> 2939, parent: i2c-1 >>>> [=C2=A0=C2=A0 27.633623] tegra-i2c 3160000.i2c: i2c transfer timed out >>>> [=C2=A0=C2=A0 27.639162] pca953x 1-0074: Unable to sync registers 0x3-= 0x5. -110 >>>> [=C2=A0=C2=A0 27.645336] pca953x 1-0074: Failed to sync GPIO dir regis= ters: -110 >>>> [=C2=A0=C2=A0 27.651596] PM: dpm_run_callback(): pca953x_resume+0x0/0x= 1b0 >>>> returns -110 >>>> [=C2=A0=C2=A0 27.658375] pca953x 1-0074: pca953x_resume+0x0/0x1b0 retu= rned -110 >>>> after 127152 usecs >>>> [=C2=A0=C2=A0 27.666194] PM: Device 1-0074 failed to resume: error -11= 0 >>>> >>>> 2) Tegra I2C transfer timeout error on jetson Xavier post resume. >>>> >>>> Signed-off-by: Bitan Biswas >>>> --- >>>> =C2=A0 drivers/i2c/busses/i2c-tegra.c | 24 ++++++++++++++++++++++++ >>>> =C2=A0 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) >>>> =C2=A0 } >>>> =C2=A0 =C2=A0 #ifdef CONFIG_PM_SLEEP >>>> +static int tegra_i2c_suspend(struct device *dev) >>>> +{ >>>> +=C2=A0=C2=A0=C2=A0 struct tegra_i2c_dev *i2c_dev =3D dev_get_drvdata(= dev); >>>> + >>>> +=C2=A0=C2=A0=C2=A0 i2c_mark_adapter_suspended(&i2c_dev->adapter); >>>> + >>>> +=C2=A0=C2=A0=C2=A0 return 0; >>>> +} >>>> + >>>> +static int tegra_i2c_resume(struct device *dev) >>>> +{ >>>> +=C2=A0=C2=A0=C2=A0 struct tegra_i2c_dev *i2c_dev =3D dev_get_drvdata(= dev); >>>> +=C2=A0=C2=A0=C2=A0 int ret; >>>> + >>>> +=C2=A0=C2=A0=C2=A0 i2c_lock_bus(&i2c_dev->adapter, I2C_LOCK_ROOT_ADAP= TER); >>>> +=C2=A0=C2=A0=C2=A0 ret =3D tegra_i2c_init(i2c_dev, false); >>>> +=C2=A0=C2=A0=C2=A0 i2c_unlock_bus(&i2c_dev->adapter, I2C_LOCK_ROOT_AD= APTER); >>> >>> 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. >=20 > 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=20 dependency. Since lock is the first call in i2c-tegra I believe I2C=20 calls of client will not start. >=20 > 2) The whole point of the i2c_mark_adapter_* API is to catch those > faulty clients that have a broken suspend-resume sequence. Client will > get a -ESHUTDOWN on trying to issue I2C transfer while controller is > marked as suspended. i2c lock bus calls were used in the resume callback implementation that=20 was reverted few months back. Hence, these were added in this patch=20 which should be more like a revert-of-revert . But I feel probably your point also makes sense. Old resume callback did=20 not have i2c_mark_adapter_* calls. Based on the i2c_adapter_mark_* API=20 documentation it should be taking care that core i2c calls from client=20 are not started. I plan to update the patch and remove the lock-unlock=20 guards in resume callback. >=20 > 3) Please don't use async suspend-resume where it doesn't make sense. This is a system wide setting. /sys/power/pm_async by default is 1 and=20 there is no driver specific change in this patch to choose async=20 suspend-resume. >=20 > Corollary: you should drop the locking because it doesn't do anything > useful. >=20 I did some basic suspend resume tests and do not see any problems=20 removing the i2c_lock_bus call you pointed out. -Thanks, Bitan