From: Richard Zhu <hongxing.zhu@nxp.com>
To: Mark Brown <broonie@kernel.org>,
Francesco Dolcini <francesco.dolcini@toradex.com>
Cc: "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: Tue, 26 Oct 2021 02:18:18 +0000 [thread overview]
Message-ID: <AS8PR04MB8676A0F3DA3248C6A27801148C849@AS8PR04MB8676.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <YXaTxDJjhpcj5XBV@sirena.org.uk>
> -----Original Message-----
> From: Mark Brown <broonie@kernel.org>
> Sent: Monday, October 25, 2021 7:24 PM
> To: Francesco Dolcini <francesco.dolcini@toradex.com>
> Cc: Richard Zhu <hongxing.zhu@nxp.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 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
next prev parent reply other threads:[~2021-10-26 2:18 UTC|newest]
Thread overview: 24+ 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 ` [PATCH v3 1/7] PCI: imx6: Encapsulate the clock enable into one standalone function 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 ` [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never came up Richard Zhu
2021-10-25 11:13 ` Francesco Dolcini
2021-10-25 11:23 ` Mark Brown
2021-10-26 2:18 ` Richard Zhu [this message]
2021-10-26 8:52 ` Francesco Dolcini
2021-10-26 9:06 ` Richard Zhu
2021-10-26 9:11 ` Francesco Dolcini
2021-10-26 9:18 ` Richard Zhu
2021-10-26 9:48 ` Francesco Dolcini
2021-10-28 6:48 ` Richard Zhu
2021-10-26 10:58 ` Mark Brown
2021-10-28 6:50 ` Richard Zhu
2021-10-28 11:50 ` Mark Brown
2021-10-29 3:58 ` Richard Zhu
2021-10-29 11:46 ` Mark Brown
2021-11-01 1:46 ` 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 ` [PATCH v3 5/7] PCI: dwc: add a new callback host exit function into host ops 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 ` [PATCH v3 7/7] PCI: imx6: Add the compliance tests mode support Richard Zhu
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