linux-kernel - RE: [PATCH v14 14/17] PCI: imx6: Do not hide phy driver callbacks and refine the error handling

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Date:   Wed, 13 Jul 2022 10:57:51 +0000
From:   Hongxing Zhu <hongxing.zhu@....com>
To:     Lucas Stach <l.stach@...gutronix.de>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "festevam@...il.com" <festevam@...il.com>,
        "francesco.dolcini@...adex.com" <francesco.dolcini@...adex.com>
CC:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH v14 14/17] PCI: imx6: Do not hide phy driver callbacks and
 refine the error handling

> -----Original Message-----
> From: Lucas Stach <l.stach@...gutronix.de>
> Sent: 2022年7月13日 16:59
> To: Hongxing Zhu <hongxing.zhu@....com>; bhelgaas@...gle.com;
> robh+dt@...nel.org; broonie@...nel.org; lorenzo.pieralisi@....com;
> festevam@...il.com; francesco.dolcini@...adex.com
> Cc: linux-pci@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
> linux-kernel@...r.kernel.org; kernel@...gutronix.de; dl-linux-imx
> <linux-imx@....com>
> Subject: Re: [PATCH v14 14/17] PCI: imx6: Do not hide phy driver callbacks and
> refine the error handling
> 
> Am Freitag, dem 01.07.2022 um 11:25 +0800 schrieb Richard Zhu:
> > - Move the phy_power_on() to host_init from imx6_pcie_clk_enable().
> > - Move the phy_init() to host_init from imx6_pcie_deassert_core_reset().
> >
> > Refine the error handling in imx6_pcie_host_init() accordingly.
> >
> > Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> > Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> > ---
> >  drivers/pci/controller/dwc/pci-imx6.c | 34 +++++++++++++++++----------
> >  1 file changed, 21 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> b/drivers/pci/controller/dwc/pci-imx6.c
> > index 5a06fbca82d6..0b2a5256fb0d 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -639,14 +639,6 @@ static int imx6_pcie_clk_enable(struct imx6_pcie
> *imx6_pcie)
> >  		goto err_ref_clk;
> >  	}
> >
> > -	switch (imx6_pcie->drvdata->variant) {
> > -	case IMX8MM:
> > -		if (phy_power_on(imx6_pcie->phy))
> > -			dev_err(dev, "unable to power on PHY\n");
> > -		break;
> > -	default:
> > -		break;
> > -	}
> >  	/* allow the clocks to stabilize */
> >  	usleep_range(200, 500);
> >  	return 0;
> > @@ -723,10 +715,6 @@ static int imx6_pcie_deassert_core_reset(struct
> imx6_pcie *imx6_pcie)
> >  	case IMX8MQ:
> >  		reset_control_deassert(imx6_pcie->pciephy_reset);
> >  		break;
> > -	case IMX8MM:
> > -		if (phy_init(imx6_pcie->phy))
> > -			dev_err(dev, "waiting for phy ready timeout!\n");
> > -		break;
> >  	case IMX7D:
> >  		reset_control_deassert(imx6_pcie->pciephy_reset);
> >
> > @@ -762,6 +750,7 @@ static int imx6_pcie_deassert_core_reset(struct
> imx6_pcie *imx6_pcie)
> >  		usleep_range(200, 500);
> >  		break;
> >  	case IMX6Q:		/* Nothing to do */
> > +	case IMX8MM:
> >  		break;
> >  	}
> >
> > @@ -913,17 +902,36 @@ static int imx6_pcie_host_init(struct pcie_port
> *pp)
> >  			return ret;
> >  		}
> >  	}
> > +	if (imx6_pcie->phy) {
> > +		ret = phy_power_on(imx6_pcie->phy);
> > +		if (ret) {
> > +			dev_err(dev, "pcie phy power up failed.\n");
> > +			goto err_reg_disable;
> > +		}
> > +	}
> >
> >  	ret = imx6_pcie_deassert_core_reset(imx6_pcie);
> >  	if (ret < 0) {
> >  		dev_err(dev, "pcie deassert core reset failed: %d\n", ret);
> > -		goto err_reg_disable;
> > +		goto err_phy_off;
> >  	}
> >
> > +	if (imx6_pcie->phy) {
> > +		ret = phy_init(imx6_pcie->phy);
> > +		if (ret) {
> > +			dev_err(dev, "waiting for phy ready timeout!\n");
> > +			goto err_clk_disable;
> > +		}
> > +	}
> 
> Wouldn't it be more logical to put this into imx6_pcie_init_phy()?
> 
Before adding i.MX8MM PCIe support, the imx6_pcie_init_phy() only touches the
 GPR registers. PCIe clocks and so on are not required in this case.
But phy_init() used by i.MX8MM PCIe touches not only the GPR registers but
 also the PHY's registers.
The clocks should be on and resets of PHY should be configured properly when
 phy_init() is invoked.
So, phy_init() is placed behind of imx6_pcie_deassert_core_reset() here.

Best Regards
Richard Zhu

> Regards,
> Lucas
> 
> >  	imx6_setup_phy_mpll(imx6_pcie);
> >
> >  	return 0;
> >
> > +err_clk_disable:
> > +	imx6_pcie_clk_disable(imx6_pcie);
> > +err_phy_off:
> > +	if (imx6_pcie->phy)
> > +		phy_power_off(imx6_pcie->phy);
> >  err_reg_disable:
> >  	if (imx6_pcie->vpcie)
> >  		regulator_disable(imx6_pcie->vpcie);
>