linux-kernel - Re: [PATCH v4 02/15] PCI: imx6: Simplify phy handling by using by using IMX6_PCIE_FLAG_HAS

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Message-ID: <ZYBYti+6So+tXhp9@lizhi-Precision-Tower-5810>
Date: Mon, 18 Dec 2023 09:35:34 -0500
From: Frank Li <Frank.li@....com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: krzysztof.kozlowski@...aro.org, bhelgaas@...gle.com,
	conor+dt@...nel.org, devicetree@...r.kernel.org, festevam@...il.com,
	helgaas@...nel.org, hongxing.zhu@....com, imx@...ts.linux.dev,
	kernel@...gutronix.de, krzysztof.kozlowski+dt@...aro.org,
	kw@...ux.com, l.stach@...gutronix.de,
	linux-arm-kernel@...ts.infradead.org, linux-imx@....com,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	lpieralisi@...nel.org, robh@...nel.org, s.hauer@...gutronix.de,
	shawnguo@...nel.org
Subject: Re: [PATCH v4 02/15] PCI: imx6: Simplify phy handling by using by
 using IMX6_PCIE_FLAG_HAS_PHY

On Sun, Dec 17, 2023 at 10:48:11PM +0530, Manivannan Sadhasivam wrote:
> On Sun, Dec 17, 2023 at 12:11:57AM -0500, Frank Li wrote:
> > Refactors the phy handling logic in the imx6 PCI driver by adding
> > IMX6_PCIE_FLAG_HAS_PHY bitmask define for drvdata::flags.
> > 
> > The drvdata::flags and a bitmask ensures a cleaner and more scalable
> > switch-case structure for handling phy.
> > 
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> > 
> > Notes:
> >     Change from v1 to v3:
> >     - none
> > 
> >  drivers/pci/controller/dwc/pci-imx6.c | 23 ++++++++++++++++-------
> >  1 file changed, 16 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> > index 2086214345e9a..91ba26a4b4c3d 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -60,6 +60,9 @@ enum imx6_pcie_variants {
> >  #define IMX6_PCIE_FLAG_IMX6_PHY			BIT(0)
> >  #define IMX6_PCIE_FLAG_IMX6_SPEED_CHANGE	BIT(1)
> >  #define IMX6_PCIE_FLAG_SUPPORTS_SUSPEND		BIT(2)
> > +#define IMX6_PCIE_FLAG_HAS_PHY			BIT(3)
> > +
> > +#define imx6_check_flag(pci, val)     (pci->drvdata->flags & val)
> >  
> >  #define IMX6_PCIE_MAX_CLKS       6
> >  
> > @@ -1277,6 +1280,13 @@ static int imx6_pcie_probe(struct platform_device *pdev)
> >  	if (ret)
> >  		return ret;
> >  
> > +	if (imx6_check_flag(imx6_pcie, IMX6_PCIE_FLAG_HAS_PHY)) {
> > +		imx6_pcie->phy = devm_phy_get(dev, "pcie-phy");
> 
> Can't you use devm_phy_optional_get()? This will return NULL if the PHY is not
> defined in DT. So you can use IS_ERR() to catch error if there are issues in
> acquiring PHY if defined and NULL can be safely passed to other PHY APIs like
> phy_init() as well.
> 
> With this, you won't need a flag in drv_data and can also get rid of the
> condition around PHY APIs.

The key is the driver need know which platform "pcie-phy" is manditary. 
devm_phy_optional_get() can work if dts is correct. use HAS_PHY flags just
double check if dts correct add "pcie-phy" at dts.

This is just one place to check. and Help debug dtb miss match issues.

Frank

> 
> - Mani
> 
> > +		if (IS_ERR(imx6_pcie->phy))
> > +			return dev_err_probe(dev, PTR_ERR(imx6_pcie->phy),
> > +					     "failed to get pcie phy\n");
> > +	}
> > +
> >  	switch (imx6_pcie->drvdata->variant) {
> >  	case IMX7D:
> >  		if (dbi_base->start == IMX8MQ_PCIE2_BASE_ADDR)
> > @@ -1306,11 +1316,6 @@ static int imx6_pcie_probe(struct platform_device *pdev)
> >  			return dev_err_probe(dev, PTR_ERR(imx6_pcie->apps_reset),
> >  					     "failed to get pcie apps reset control\n");
> >  
> > -		imx6_pcie->phy = devm_phy_get(dev, "pcie-phy");
> > -		if (IS_ERR(imx6_pcie->phy))
> > -			return dev_err_probe(dev, PTR_ERR(imx6_pcie->phy),
> > -					     "failed to get pcie phy\n");
> > -
> >  		break;
> >  	default:
> >  		break;
> > @@ -1447,13 +1452,15 @@ static const struct imx6_pcie_drvdata drvdata[] = {
> >  	},
> >  	[IMX8MM] = {
> >  		.variant = IMX8MM,
> > -		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND,
> > +		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND |
> > +			 IMX6_PCIE_FLAG_HAS_PHY,
> >  		.gpr = "fsl,imx8mm-iomuxc-gpr",
> >  		.clk_names = {IMX6_CLKS_COMMON, "pcie_aux"},
> >  	},
> >  	[IMX8MP] = {
> >  		.variant = IMX8MP,
> > -		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND,
> > +		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND |
> > +			 IMX6_PCIE_FLAG_HAS_PHY,
> >  		.gpr = "fsl,imx8mp-iomuxc-gpr",
> >  		.clk_names = {IMX6_CLKS_COMMON, "pcie_aux"},
> >  	},
> > @@ -1465,12 +1472,14 @@ static const struct imx6_pcie_drvdata drvdata[] = {
> >  	},
> >  	[IMX8MM_EP] = {
> >  		.variant = IMX8MM_EP,
> > +		.flags = IMX6_PCIE_FLAG_HAS_PHY,
> >  		.mode = DW_PCIE_EP_TYPE,
> >  		.gpr = "fsl,imx8mm-iomuxc-gpr",
> >  		.clk_names = {IMX6_CLKS_COMMON, "pcie_aux"},
> >  	},
> >  	[IMX8MP_EP] = {
> >  		.variant = IMX8MP_EP,
> > +		.flags = IMX6_PCIE_FLAG_HAS_PHY,
> >  		.mode = DW_PCIE_EP_TYPE,
> >  		.gpr = "fsl,imx8mp-iomuxc-gpr",
> >  		.clk_names = {IMX6_CLKS_COMMON, "pcie_aux"},
> > -- 
> > 2.34.1
> > 
> 
> -- 
> மணிவண்ணன் சதாசிவம்