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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: AS8PR04MB8676.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 485c7df0-8ca6-4ad8-f4f0-08d99826dff7 X-MS-Exchange-CrossTenant-originalarrivaltime: 26 Oct 2021 02:18:18.2577 (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: Z8NmvxsOKnwgBO8cgy4QtBW0EdJG151QXp0lgf5+lrtIRK/vi6x8kKh/MMLxeVcFBKFcRLSUXX4n+P8wXtNdLw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: AS8PR04MB8803 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Mark Brown > Sent: Monday, October 25, 2021 7:24 PM > To: Francesco Dolcini > Cc: Richard Zhu ; l.stach@pengutronix.de; > bhelgaas@google.com; lorenzo.pieralisi@arm.com; jingoohan1@gmail.com; > linux-pci@vger.kernel.org; dl-linux-imx ; > linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org; > kernel@pengutronix.de > Subject: Re: [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link n= ever > came up >=20 > On Mon, Oct 25, 2021 at 01:13:12PM +0200, Francesco Dolcini wrote: >=20 > > Hello Richard, > > please see this comment from Mark, > https://lore.kernel.org/all/YXaGve1ZJq0DGZ9l@sirena.org.uk/. >=20 > > > + if (imx6_pcie->vpcie > > > + && regulator_is_enabled(imx6_pcie->vpcie) > 0) > > > + regulator_disable(imx6_pcie->vpcie); > > > return ret; >=20 > I should probably also say that the check for the regulator looks buggy a= s well, > regulators should only be optional if they can be physically absent which= does > not seem likely for PCI devices. If the driver is not doing something to > reconfigure the hardware to account for a missing supply this is generall= y a big > warning sign. >=20 > I really don't understand why regulator support is so frequently problema= tic > for PCI controllers. :( [Richard Zhu] Hi Mark: The _enabled check is used because that this regulator is optional in the H= W design. To make the codes clean and aligned on different HW boards, the _enabled ch= eck is added. The root cause is that the error return is not handled properly by the cont= roller driver. I.MX PCIe controller doesn't support the Hot-Plug, and it would return -110= error when PCIe link never came up. Thus, the _probe would be failed in the end. The clocks/regulator usage balance should be considered by i.MX PCIe contro= ller, that's all. It's not a general case, and the problem is not caused by the regulator sup= port. 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b=dOs/q+G4OY8z0mrsLkQ9zs42Dj9n8A8eU8a2bZKinNtb1zt9vEV/ISfjMgUFz0PSVl4wATo0cZ9X3dtiLADW/4Ffatn3bffrwSBYQyLt6RJh+3MXJH6BD2+M2h2q1vgOFyGf5RZc+BHjewAnWSIAGcNVmJ1AwbrH749jYcky9jg= Received: from AS8PR04MB8676.eurprd04.prod.outlook.com (2603:10a6:20b:42b::10) by AS8PR04MB8803.eurprd04.prod.outlook.com (2603:10a6:20b:42e::24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4628.16; Tue, 26 Oct 2021 02:18:18 +0000 Received: from AS8PR04MB8676.eurprd04.prod.outlook.com ([fe80::b059:46c6:685b:e0fc]) by AS8PR04MB8676.eurprd04.prod.outlook.com ([fe80::b059:46c6:685b:e0fc%4]) with mapi id 15.20.4628.020; Tue, 26 Oct 2021 02:18:18 +0000 From: Richard Zhu To: Mark Brown , Francesco Dolcini CC: "l.stach@pengutronix.de" , "bhelgaas@google.com" , "lorenzo.pieralisi@arm.com" , "jingoohan1@gmail.com" , "linux-pci@vger.kernel.org" , dl-linux-imx , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "kernel@pengutronix.de" Subject: RE: [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never came up Thread-Topic: [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never came up Thread-Index: AQHXxxe5hpSrQkcPqkWGr8lEYEKQh6vjlGkAgAAC9gCAAPQyAA== Date: Tue, 26 Oct 2021 02:18:18 +0000 Message-ID: References: <1634886750-13861-1-git-send-email-hongxing.zhu@nxp.com> <1634886750-13861-4-git-send-email-hongxing.zhu@nxp.com> <20211025111312.GA31419@francesco-nb.int.toradex.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nxp.com; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org > -----Original Message----- > From: Mark Brown > Sent: Monday, October 25, 2021 7:24 PM > To: Francesco Dolcini > Cc: Richard Zhu ; l.stach@pengutronix.de; > bhelgaas@google.com; lorenzo.pieralisi@arm.com; jingoohan1@gmail.com; > linux-pci@vger.kernel.org; dl-linux-imx ; > linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org; > kernel@pengutronix.de > Subject: Re: [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never > came up > > On Mon, Oct 25, 2021 at 01:13:12PM +0200, Francesco Dolcini wrote: > > > Hello Richard, > > please see this comment from Mark, > https://lore.kernel.org/all/YXaGve1ZJq0DGZ9l@sirena.org.uk/. > > > > + if (imx6_pcie->vpcie > > > + && regulator_is_enabled(imx6_pcie->vpcie) > 0) > > > + regulator_disable(imx6_pcie->vpcie); > > > return ret; > > I should probably also say that the check for the regulator looks buggy as well, > regulators should only be optional if they can be physically absent which does > not seem likely for PCI devices. If the driver is not doing something to > reconfigure the hardware to account for a missing supply this is generally a big > warning sign. > > I really don't understand why regulator support is so frequently problematic > for PCI controllers. :( [Richard Zhu] Hi Mark: The _enabled check is used because that this regulator is optional in the HW design. To make the codes clean and aligned on different HW boards, the _enabled check is added. The root cause is that the error return is not handled properly by the controller driver. I.MX PCIe controller doesn't support the Hot-Plug, and it would return -110 error when PCIe link never came up. Thus, the _probe would be failed in the end. The clocks/regulator usage balance should be considered by i.MX PCIe controller, that's all. It's not a general case, and the problem is not caused by the regulator support. Best Regards Richard Zhu _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel