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received-spf: None (protection.outlook.com: nxp.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: mpzObb8xiEsmoBdlu7Mgg8yY9yB8DmLj3wp7xA3gdrShFX4J8kzeb0MFnt4hAODP4fEuE5hM2oK0qW9C+RZ5ui1lyIs8Nnl+Ze2fXc+uV46KY+QAhhZK+kmBIxDRk64i4Og/eonk2eJaRUxyiDsOXAyhdvOsYdop7/0vNNfLxLQa5kLmhYTi3LIIW3UJ9TM2fnkU6yEn72YZr/lRbKzx8cT9bJQgkV7Pb8WVEwPztyjShMEUFJUNWC2aolYvJjVZM7p2ieurUGurscYYjgb+NYMHZOVhwGkevwn2Pe3KzX0ZKS0QuGEL39AnAIIT1jcQV6QCMI08vz4B0lF87miOURUT7NrQ3W4paVpXhpZ7ZQzv53t4lVmvPNV73ZpiBLRMi/34d3odCbjXoCgrd6A4oFeeDKPngYbUW4Cy8tWmWbM= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0f62cf8c-9d63-42b7-bf17-08d6e3d5b18e X-MS-Exchange-CrossTenant-originalarrivaltime: 29 May 2019 01:33:46.5455 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: fugang.duan@nxp.com X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR0402MB3920 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mark Brown Sent: Tuesday, May 28, 2019 9:27 PM > On Tue, May 28, 2019 at 02:20:15AM +0000, Andy Duan wrote: >=20 > > So on i.MX8MM/8QM/8QXP platforms, we catch the issue that user dump > > regmap registers without power cause system hang. > > Maybe revert the patch is more reasonable ? >=20 > This is an issue with or without a device - you can have the same issue w= ith > devices that are powered off. Typically where power is dynamic the drive= r > will use a register cache so the registers are always available. Correct, regmap without device also has issue when power if off, because re= gmap doesn't implement runtime pm for the device, but maybe device driver implem= ent the runtime pm for the device.=20 So regmap how to manage the clock and power when access registers by debugf= s ? Andy