Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
To:     Mark Jonas <mark.jonas@de.bosch.com>,
        Support Opensource <Support.Opensource@diasemi.com>,
        Lee Jones <lee.jones@linaro.org>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
        Adam Thomson <Adam.Thomson.Opensource@diasemi.com>,
        Steve Twiss <stwiss.opensource@diasemi.com>,
        "marek.vasut@gmail.com" <marek.vasut@gmail.com>,
        "tingquan.ruan@cn.bosch.com" <tingquan.ruan@cn.bosch.com>,
        "hubert.streidl@de.bosch.com" <hubert.streidl@de.bosch.com>,
        Wolfram Sang <wsa@kernel.org>
Subject: RE: [PATCH v6 1/1] mfd: da9063: Support SMBus and I2C mode
Thread-Topic: [PATCH v6 1/1] mfd: da9063: Support SMBus and I2C mode
Thread-Index: AQHXGoQ9q1Qbk9rEZUyKzkmMFfUVGKqH6xwQ
Date:   Wed, 17 Mar 2021 09:30:10 +0000
Message-ID: <PR3PR10MB41425F5C553DC7F5E67F6A77806A9@PR3PR10MB4142.EURPRD10.PROD.OUTLOOK.COM>
References: <20210316162237.877436-1-mark.jonas@de.bosch.com>
In-Reply-To: <20210316162237.877436-1-mark.jonas@de.bosch.com>
Accept-Language: en-GB, en-US
Content-Language: en-US
x-ms-exchange-messagesentrepresentingtype: 1
x-originating-ip: [147.161.166.124]
x-ms-publictraffictype: Email
x-ms-office365-filtering-correlation-id: 38c8ee81-4f38-4161-640a-08d8e92742d8
x-ms-traffictypediagnostic: PR3PR10MB3914:
x-ms-exchange-sharedmailbox-routingagent-processed: True
x-ms-exchange-transport-forked: True
x-microsoft-antispam-prvs: <PR3PR10MB3914C57FBCB58032A37633A2A76A9@PR3PR10MB3914.EURPRD10.PROD.OUTLOOK.COM>
x-ms-oob-tlc-oobclassifiers: OLM:8882;
x-ms-exchange-senderadcheck: 1
x-microsoft-antispam: BCL:0;
x-microsoft-antispam-message-info: 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
x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PR3PR10MB4142.EURPRD10.PROD.OUTLOOK.COM;PTR:;CAT:NONE;SFS:(4636009)(39850400004)(366004)(346002)(136003)(396003)(376002)(66556008)(66476007)(5660300002)(55016002)(71200400001)(33656002)(26005)(316002)(66446008)(7696005)(8676002)(54906003)(8936002)(110136005)(478600001)(9686003)(53546011)(66946007)(52536014)(64756008)(2906002)(86362001)(76116006)(4326008)(186003)(6506007)(83380400001);DIR:OUT;SFP:1101;
x-ms-exchange-antispam-messagedata: =?us-ascii?Q?pn0ikLIJf4JVzG5iD97fjTYGVDLv2HZF1J+tuVutVnLo1oa32AcylItcUag4?=
 =?us-ascii?Q?J1qeVKzZNIEmKABrvdBOBxqORx2Po/puDXFMLOhc8qU1jad0sYy9JnxxGOId?=
 =?us-ascii?Q?/CheDqJ8sTa9aLrNgAqSjaw9HUf8SfL5JBp/0IA1gQC7olToyw704rRW4rFN?=
 =?us-ascii?Q?Wc4r4ydA2VTE4+eGZ2AUtsZX89UjWiRVZw3IR5NYvm1tRPGGrHSZBdFPGz+o?=
 =?us-ascii?Q?nfcTPtE3qYvS4EcTzaWVI62MkNLBC+LB+VFz1jlAfzOSBruLwe04GsyAP6ks?=
 =?us-ascii?Q?4eSJ3EIWvcn2yBJsabE5+o3mIryDupM/iVVdlDtoknLZXwm50BrKP925RiLm?=
 =?us-ascii?Q?TOKW5tmXv+bn6sRZFQb9GaOd4A/GxfSUWcN7wZ7DOXHoMP34Z44uO+UAk9xY?=
 =?us-ascii?Q?i5A9keo6Yz9dFmazdzT33PPXCUJoyLh/tr6dX59DtT16dgyibj+rsBFdKSGj?=
 =?us-ascii?Q?KF0Ni9mf5531Pifv4IPG6pqqZdZ1RVyxMZEc9RCxpAd9elvIPxsP/noet0kR?=
 =?us-ascii?Q?3aDqYcUDCC7Dj3kGcslS38gwP8nijXQHqSQJUChbmLieojup5oya7PMsA4sv?=
 =?us-ascii?Q?XieNL5Lw40Fq0CmGnGhf11MnSih/2svlhqcOHEIEm7VPrR4xuaup+zm8dB5/?=
 =?us-ascii?Q?v/YGcpLwMmWChzjeShB2UTutSa7ZnECex1grrsEZHyi5md7kfHNZ03myhqx7?=
 =?us-ascii?Q?svKXQglA93qu4A3mjZK78YhWxiXoEQegMGtIp/0qRZiMkLOREnUs6PE6FcQo?=
 =?us-ascii?Q?VmDC2f9h51UvXy28oJmi6FKz2v/bZLjdExBBUH0prs9qe9UNnV+KD36UKd0q?=
 =?us-ascii?Q?D0a7GQSqIm54aRWv/JLCanIzwqTuc4AQVH7UfaBiVynfoxK4Hr6CnL6OQTKU?=
 =?us-ascii?Q?Oyz8Mn3yHdrufnXuhoTCnHKX7oz3mmOqFNaBVoTpm2yj0YvBh5IKuo8BW5Vp?=
 =?us-ascii?Q?roNkPZ8a4NI6LzElOXwJlPNVr2Lp0fA7c68ydhYaZrHKt97UD6v9ETkvUZ+7?=
 =?us-ascii?Q?mmiRRonbVO9EsZ9E2Yz8M2WMR3NUjUhq7tQR9vKIQqVMCXkaZpNJevtFPYmy?=
 =?us-ascii?Q?XCjCxiZl1YSUw4Pah8AVCMFx9d9Hn6CtTDcAl+OS8cv2IC9dUDZKj6bgVX0o?=
 =?us-ascii?Q?+mgMdU+tKwUA9Jx7hlMJHv2WzJAmD2sJcD7ZEU0TrZummIPrdM0f7oYJTmsc?=
 =?us-ascii?Q?lwX+ebUOVw0rd6q/k0tp1/IgXa5TWBbfZtOS/xJJymY6nJoFKJZyMElXKzxq?=
 =?us-ascii?Q?PHiHnpcAgZ6amuhaLLeDDG337xT34jprXycACd1lp2WUID++piIt+oqOObmp?=
 =?us-ascii?Q?/q1sHNIad/vIpJ2kY6VeB0as?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: diasemi.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: PR3PR10MB4142.EURPRD10.PROD.OUTLOOK.COM
X-MS-Exchange-CrossTenant-Network-Message-Id: 38c8ee81-4f38-4161-640a-08d8e92742d8
X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Mar 2021 09:30:10.6045
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 511e3c0e-ee96-486e-a2ec-e272ffa37b7c
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: inp9FRoEp8dlAuYNDaUw58qhSqIprvfJnkIhuyXWe4fU0UIauWBYDI3l260JhrKV/duwXtdIiv+wBLvOy77dAxRPU2Ckx6HwM0R9rJ8LJvc=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PR3PR10MB3914
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 16 March 2021 16:23, Mark Jonas wrote:

> From: Hubert Streidl <hubert.streidl@de.bosch.com>
>=20
> By default the PMIC DA9063 2-wire interface is SMBus compliant. This
> means the PMIC will automatically reset the interface when the clock
> signal ceases for more than the SMBus timeout of 35 ms.
>=20
> If the I2C driver / device is not capable of creating atomic I2C
> transactions, a context change can cause a ceasing of the clock signal.
> This can happen if for example a real-time thread is scheduled. Then
> the DA9063 in SMBus mode will reset the 2-wire interface. Subsequently
> a write message could end up in the wrong register. This could cause
> unpredictable system behavior.
>=20
> The DA9063 PMIC also supports an I2C compliant mode for the 2-wire
> interface. This mode does not reset the interface when the clock
> signal ceases. Thus the problem depicted above does not occur.
>=20
> This patch tests for the bus functionality "I2C_FUNC_I2C". It can
> reasonably be assumed that the bus cannot obey SMBus timings if
> this functionality is set. SMBus commands most probably are emulated
> in this case which is prone to the latency issue described above.
>=20
> This patch enables the I2C bus mode if I2C_FUNC_I2C is set or
> otherwise keeps the default SMBus mode.
>=20
> Signed-off-by: Hubert Streidl <hubert.streidl@de.bosch.com>
> Signed-off-by: Mark Jonas <mark.jonas@de.bosch.com>

Thanks for your efforts on this Mark.