From: Richard Zhu <hongxing.zhu@nxp.com> To: Mark Brown <broonie@kernel.org> Cc: Francesco Dolcini <francesco.dolcini@toradex.com>, "l.stach@pengutronix.de" <l.stach@pengutronix.de>, "bhelgaas@google.com" <bhelgaas@google.com>, "lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>, "jingoohan1@gmail.com" <jingoohan1@gmail.com>, "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>, dl-linux-imx <linux-imx@nxp.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "kernel@pengutronix.de" <kernel@pengutronix.de> Subject: RE: [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never came up Date: Fri, 29 Oct 2021 03:58:41 +0000 [thread overview] Message-ID: <AS8PR04MB8676CF52F4D8E9E4E6C07F758C879@AS8PR04MB8676.eurprd04.prod.outlook.com> (raw) In-Reply-To: <YXqOcAIO2aYkr1sM@sirena.org.uk> > -----Original Message----- > From: Mark Brown <broonie@kernel.org> > Sent: Thursday, October 28, 2021 7:50 PM > To: Richard Zhu <hongxing.zhu@nxp.com> > Cc: Francesco Dolcini <francesco.dolcini@toradex.com>; > l.stach@pengutronix.de; bhelgaas@google.com; > lorenzo.pieralisi@arm.com; jingoohan1@gmail.com; > linux-pci@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>; > 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 Thu, Oct 28, 2021 at 06:50:58AM +0000, Richard Zhu wrote: > > > > I would be really surprised to see PCI hardware that was able to > > > support a supply being physically absent, and this use of > > > _is_enabled() is quite simply not how any of this is supposed to > > > work in the regulator API even for regulators that can be optional. > > > [Richard Zhu] Actually, this regulator is one GPIO fixed regulator. > > Controlled by SW to turn on (GPIO high) or turn off (GPIO low) the > supply. > > In some boards designs, this supply might be always on(GPIO high). > > So, in point of SW driver view, this regulator is optional. > > No, it's not. The regulator API supports the systems where the regualtor > is always on perfectly well, the client driver should not need to do > anything to support them. [Richard Zhu] Hi Mark: Thanks for your explains. To disable the regulator explicitly, is a part of power save of i.MX PCIe port usage when link is down. Because that this regulator might not be present at all on some boards (e.x: powered directly when board is powered up), so this regulator is optional from SW view. > > > > Perhaps it's not causing problems in this design but if the supply > > > is ever shared with anything else then the software will run into > trouble. > > > There will also be problems with the error handling on a system > > > where the regulator needs to be controlled. > > > [Richard Zhu] This GPIO fixed regulator is only used by controller driver. > > It makes sense to disable the enabled regulator when driver probe is > failed. > > The driver should undo any enables it did itself, it should not undo any > enables that anything else did which means it should never be basing > decisions on regulator_is_enabled(). While the regulator may not be > shared in the particular board you're looking at it may be shared in other > systems. [Richard Zhu] Understood. Thanks. Can I disabled this regulator in PCIe probe failure handler without the regulator_is_enabled() check? BR Richard
WARNING: multiple messages have this Message-ID (diff)
From: Richard Zhu <hongxing.zhu@nxp.com> To: Mark Brown <broonie@kernel.org> Cc: Francesco Dolcini <francesco.dolcini@toradex.com>, "l.stach@pengutronix.de" <l.stach@pengutronix.de>, "bhelgaas@google.com" <bhelgaas@google.com>, "lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>, "jingoohan1@gmail.com" <jingoohan1@gmail.com>, "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>, dl-linux-imx <linux-imx@nxp.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "kernel@pengutronix.de" <kernel@pengutronix.de> Subject: RE: [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never came up Date: Fri, 29 Oct 2021 03:58:41 +0000 [thread overview] Message-ID: <AS8PR04MB8676CF52F4D8E9E4E6C07F758C879@AS8PR04MB8676.eurprd04.prod.outlook.com> (raw) In-Reply-To: <YXqOcAIO2aYkr1sM@sirena.org.uk> > -----Original Message----- > From: Mark Brown <broonie@kernel.org> > Sent: Thursday, October 28, 2021 7:50 PM > To: Richard Zhu <hongxing.zhu@nxp.com> > Cc: Francesco Dolcini <francesco.dolcini@toradex.com>; > l.stach@pengutronix.de; bhelgaas@google.com; > lorenzo.pieralisi@arm.com; jingoohan1@gmail.com; > linux-pci@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>; > 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 Thu, Oct 28, 2021 at 06:50:58AM +0000, Richard Zhu wrote: > > > > I would be really surprised to see PCI hardware that was able to > > > support a supply being physically absent, and this use of > > > _is_enabled() is quite simply not how any of this is supposed to > > > work in the regulator API even for regulators that can be optional. > > > [Richard Zhu] Actually, this regulator is one GPIO fixed regulator. > > Controlled by SW to turn on (GPIO high) or turn off (GPIO low) the > supply. > > In some boards designs, this supply might be always on(GPIO high). > > So, in point of SW driver view, this regulator is optional. > > No, it's not. The regulator API supports the systems where the regualtor > is always on perfectly well, the client driver should not need to do > anything to support them. [Richard Zhu] Hi Mark: Thanks for your explains. To disable the regulator explicitly, is a part of power save of i.MX PCIe port usage when link is down. Because that this regulator might not be present at all on some boards (e.x: powered directly when board is powered up), so this regulator is optional from SW view. > > > > Perhaps it's not causing problems in this design but if the supply > > > is ever shared with anything else then the software will run into > trouble. > > > There will also be problems with the error handling on a system > > > where the regulator needs to be controlled. > > > [Richard Zhu] This GPIO fixed regulator is only used by controller driver. > > It makes sense to disable the enabled regulator when driver probe is > failed. > > The driver should undo any enables it did itself, it should not undo any > enables that anything else did which means it should never be basing > decisions on regulator_is_enabled(). While the regulator may not be > shared in the particular board you're looking at it may be shared in other > systems. [Richard Zhu] Understood. Thanks. Can I disabled this regulator in PCIe probe failure handler without the regulator_is_enabled() check? BR Richard _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-10-29 3:58 UTC|newest] Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-22 7:12 [PATCH v3 0/7] PCI: imx6: refine codes and add compliance tests mode support Richard Zhu 2021-10-22 7:12 ` Richard Zhu 2021-10-22 7:12 ` [PATCH v3 1/7] PCI: imx6: Encapsulate the clock enable into one standalone function Richard Zhu 2021-10-22 7:12 ` Richard Zhu 2021-10-22 7:12 ` [PATCH v3 2/7] PCI: imx6: Add the error propagation from host_init Richard Zhu 2021-10-22 7:12 ` Richard Zhu 2021-10-22 7:12 ` [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never came up Richard Zhu 2021-10-22 7:12 ` Richard Zhu 2021-10-25 11:13 ` Francesco Dolcini 2021-10-25 11:13 ` Francesco Dolcini 2021-10-25 11:23 ` Mark Brown 2021-10-25 11:23 ` Mark Brown 2021-10-26 2:18 ` Richard Zhu 2021-10-26 2:18 ` Richard Zhu 2021-10-26 8:52 ` Francesco Dolcini 2021-10-26 8:52 ` Francesco Dolcini 2021-10-26 9:06 ` Richard Zhu 2021-10-26 9:06 ` Richard Zhu 2021-10-26 9:11 ` Francesco Dolcini 2021-10-26 9:11 ` Francesco Dolcini 2021-10-26 9:18 ` Richard Zhu 2021-10-26 9:18 ` Richard Zhu 2021-10-26 9:48 ` Francesco Dolcini 2021-10-26 9:48 ` Francesco Dolcini 2021-10-28 6:48 ` Richard Zhu 2021-10-28 6:48 ` Richard Zhu 2021-10-26 10:58 ` Mark Brown 2021-10-26 10:58 ` Mark Brown 2021-10-28 6:50 ` Richard Zhu 2021-10-28 6:50 ` Richard Zhu 2021-10-28 11:50 ` Mark Brown 2021-10-28 11:50 ` Mark Brown 2021-10-29 3:58 ` Richard Zhu [this message] 2021-10-29 3:58 ` Richard Zhu 2021-10-29 11:46 ` Mark Brown 2021-10-29 11:46 ` Mark Brown 2021-11-01 1:46 ` Richard Zhu 2021-11-01 1:46 ` Richard Zhu 2021-10-26 1:57 ` Richard Zhu 2021-10-26 1:57 ` Richard Zhu 2021-10-22 7:12 ` [PATCH v3 4/7] PCI: imx6: move the clock disable function to a proper place Richard Zhu 2021-10-22 7:12 ` Richard Zhu 2021-10-22 7:12 ` [PATCH v3 5/7] PCI: dwc: add a new callback host exit function into host ops Richard Zhu 2021-10-22 7:12 ` Richard Zhu 2021-10-22 7:12 ` [PATCH v3 6/7] PCI: imx6: Fix the reference handling unbalance when link never came up Richard Zhu 2021-10-22 7:12 ` Richard Zhu 2021-10-22 7:12 ` [PATCH v3 7/7] PCI: imx6: Add the compliance tests mode support Richard Zhu 2021-10-22 7:12 ` Richard Zhu
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