RE: [PATCH v10 5/7] PCI: imx6: Turn off regulator when the system is in suspend mode

From: Hongxing Zhu <hongxing.zhu@nxp.com>
To: Francesco Dolcini <francesco.dolcini@toradex.com>,
	"l.stach@pengutronix.de" <l.stach@pengutronix.de>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	"robh@kernel.org" <robh@kernel.org>
Cc: "broonie@kernel.org" <broonie@kernel.org>,
	"lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>,
	"festevam@gmail.com" <festevam@gmail.com>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"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>,
	dl-linux-imx <linux-imx@nxp.com>
Subject: RE: [PATCH v10 5/7] PCI: imx6: Turn off regulator when the system is in suspend mode
Date: Tue, 14 Jun 2022 00:58:34 +0000	[thread overview]
Message-ID: <DU2PR04MB86774EED49C2928B48A4B7228CAA9@DU2PR04MB8677.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20220613101712.GA20538@francesco-nb.int.toradex.com>

> -----Original Message-----
> From: Francesco Dolcini <francesco.dolcini@toradex.com>
> Sent: 2022年6月13日 18:17
> To: Hongxing Zhu <hongxing.zhu@nxp.com>; l.stach@pengutronix.de;
> bhelgaas@google.com; robh@kernel.org
> Cc: broonie@kernel.org; lorenzo.pieralisi@arm.com; festevam@gmail.com;
> francesco.dolcini@toradex.com; linux-pci@vger.kernel.org;
> linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org;
> kernel@pengutronix.de; dl-linux-imx <linux-imx@nxp.com>
> Subject: Re: [PATCH v10 5/7] PCI: imx6: Turn off regulator when the system is
> in suspend mode
> 
> On Mon, Jun 13, 2022 at 04:55:36PM +0800, Richard Zhu wrote:
> > The driver should undo any enables it did itself. The regulator
> > disable shouldn't be basing decisions on regulator_is_enabled().
> >
> > Move the regulator_disable to the suspend function, turn off regulator
> > when the system is in suspend mode.
> 
> According to the documentation:
> 
>   vpcie-supply:
>     description: Should specify the regulator in charge of PCIe port power.
>       The regulator will be enabled when initializing the PCIe host and
>       disabled either as part of the init process or when shutting down
>       the host (optional required).
> 
> Is this really what we want to do (remove power in suspend, enable it on
> resume)? On our boards this powers a PCIe device connected to the host port,
> that sound fair according to the binding documentation for it.
> Am I wrong?
> 
> We do have issues with PCIe not working anymore after suspend/resume,
> wondering (I did not have time to properly dig into it) if this is the root cause.
> 
Hi Francesco:
Yes, you're right. This regulator is used to powered up the port. It's
 reasonable to move the disable to suspend refer to Lucas' review comments.
BTW, I suspect that your PCIe failure after suspend/resume is caused by the
 MSI_ADDR missing. Can you make a double check on it?
I used found that the MSI_ADDR should be re-configured again during resume on
 some platforms. But I didn't issue that fix patch in time. Sorry about that.

Best Regards
Richard Zhu

> Francesco