linux-kernel - RE: [PATCHv5 17/20] PCI: mobiveil: Complete initialization of host even if no PCIe link

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Message-ID: <AM0PR04MB6738A753FB8A0AE340ADB2C684E90@AM0PR04MB6738.eurprd04.prod.outlook.com>
Date:   Sat, 15 Jun 2019 02:34:44 +0000
From:   "Z.q. Hou" <zhiqiang.hou@....com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
CC:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "l.subrahmanya@...iveil.co.in" <l.subrahmanya@...iveil.co.in>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        Leo Li <leoyang.li@....com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will.deacon@....com" <will.deacon@....com>,
        Mingkai Hu <mingkai.hu@....com>,
        "M.h. Lian" <minghuan.lian@....com>,
        Xiaowei Bao <xiaowei.bao@....com>
Subject: RE: [PATCHv5 17/20] PCI: mobiveil: Complete initialization of host
 even if no PCIe link

Hi Lorenzo,

> -----Original Message-----
> From: Lorenzo Pieralisi [mailto:lorenzo.pieralisi@....com]
> Sent: 2019年6月12日 22:35
> To: Z.q. Hou <zhiqiang.hou@....com>
> Cc: linux-pci@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
> devicetree@...r.kernel.org; linux-kernel@...r.kernel.org;
> bhelgaas@...gle.com; robh+dt@...nel.org; mark.rutland@....com;
> l.subrahmanya@...iveil.co.in; shawnguo@...nel.org; Leo Li
> <leoyang.li@....com>; catalin.marinas@....com; will.deacon@....com;
> Mingkai Hu <mingkai.hu@....com>; M.h. Lian <minghuan.lian@....com>;
> Xiaowei Bao <xiaowei.bao@....com>
> Subject: Re: [PATCHv5 17/20] PCI: mobiveil: Complete initialization of host
> even if no PCIe link
> 
> On Fri, Apr 12, 2019 at 08:36:54AM +0000, Z.q. Hou wrote:
> > From: Hou Zhiqiang <Zhiqiang.Hou@....com>
> >
> > Sometimes there is not a PCIe Endpoint stalled in the slot, so do not
> > exit when the PCIe link is not up. And degrade the print level of link
> > up info.
> 
> So what's the point of probing if the link does not initialize ?

A simple case is plug in a PCIe device after the Linux boot up, then rescan the device.
If exit when PCIe link is not up, the PCIe controller is not initialized completely, the
rescan cannot work.

Thanks,
Zhiqiang

> Lorenzo
> 
> > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@....com>
> > Reviewed-by: Minghuan Lian <Minghuan.Lian@....com>
> > Reviewed-by: Subrahmanya Lingappa <l.subrahmanya@...iveil.co.in>
> > ---
> > V5:
> >  - Corrected and retouched the subject and changelog.
> >
> >  drivers/pci/controller/pcie-mobiveil.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pcie-mobiveil.c
> > b/drivers/pci/controller/pcie-mobiveil.c
> > index 1ee3ea2570c0..8dc87c7a600e 100644
> > --- a/drivers/pci/controller/pcie-mobiveil.c
> > +++ b/drivers/pci/controller/pcie-mobiveil.c
> > @@ -560,7 +560,7 @@ static int mobiveil_bringup_link(struct
> mobiveil_pcie *pcie)
> >  		usleep_range(LINK_WAIT_MIN, LINK_WAIT_MAX);
> >  	}
> >
> > -	dev_err(&pcie->pdev->dev, "link never came up\n");
> > +	dev_info(&pcie->pdev->dev, "link never came up\n");
> >
> >  	return -ETIMEDOUT;
> >  }
> > @@ -926,10 +926,8 @@ static int mobiveil_pcie_probe(struct
> platform_device *pdev)
> >  	bridge->swizzle_irq = pci_common_swizzle;
> >
> >  	ret = mobiveil_bringup_link(pcie);
> > -	if (ret) {
> > +	if (ret)
> >  		dev_info(dev, "link bring-up failed\n");
> > -		goto error;
> > -	}
> >
> >  	/* setup the kernel resources for the newly added PCIe root bus */
> >  	ret = pci_scan_root_bus_bridge(bridge);
> > --
> > 2.17.1
> >