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Date:   Tue, 12 Dec 2023 13:32:11 -0500
From:   Frank Li <Frank.li@....com>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     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 v3 01/13] PCI: imx6: Simplify clock handling by using
 HAS_CLK_* bitmask

On Tue, Dec 12, 2023 at 10:19:13PM +0530, Manivannan Sadhasivam wrote:
> On Mon, Dec 11, 2023 at 04:58:30PM -0500, Frank Li wrote:
> > Refactors the clock handling logic in the imx6 PCI driver by adding
> > HAS_CLK_* bitmask define for drvdata::flags . Simplifies the code and makes
> > it more maintainable, as future additions of SOC support will only require
> > straightforward changes. The drvdata::flags and a bitmask ensures a cleaner
> > and more scalable switch-case structure for handling clocks.
> > 
> 
> Is there any necessity to validate each clock in the driver? I mean, can't you
> just rely on devicetree to provide enough clocks for the functioning of the PCIe
> controller?
> 
> If you can rely on devicetree (everyone should in an ideal world), then you can
> just use devm_clk_bulk_get_all() to get all available clocks for the SoC and
> just enable/disable whatever is available.
> 
> This will greatly simplify the code.
> 
> Only downside of this approach is, if the devicetree is not supplying enough
> clocks, then it will be difficult to find why PCIe is not working. But this also
> means that the devicetree is screwed.

I have idea, how about add clk name array in drvdata.

such as
      clk_names[] = {"bus", "aux", "axi", ...}
      clk_cnt = 4.

Then use devm_clk_blk_get_all().

Code will be simplied and not too much depend on devicetree's validate.

Frank

> 
> - Mani
> 
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> > 
> > Notes:
> >     Change from v1 to v3
> >     - none
> > 
> >  drivers/pci/controller/dwc/pci-imx6.c | 84 +++++++++++++--------------
> >  1 file changed, 42 insertions(+), 42 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> > index 74703362aeec7..8a9b527934f80 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -60,6 +60,10 @@ 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_CLK_INBOUND_AXI	BIT(3)
> > +#define IMX6_PCIE_FLAG_HAS_CLK_AUX		BIT(4)
> > +
> > +#define imx6_check_flag(pci, val)	(pci->drvdata->flags & val)
> >  
> >  struct imx6_pcie_drvdata {
> >  	enum imx6_pcie_variants variant;
> > @@ -550,19 +554,23 @@ static int imx6_pcie_attach_pd(struct device *dev)
> >  
> >  static int imx6_pcie_enable_ref_clk(struct imx6_pcie *imx6_pcie)
> >  {
> > -	struct dw_pcie *pci = imx6_pcie->pci;
> > -	struct device *dev = pci->dev;
> >  	unsigned int offset;
> >  	int ret = 0;
> >  
> > -	switch (imx6_pcie->drvdata->variant) {
> > -	case IMX6SX:
> > +	if (imx6_check_flag(imx6_pcie, IMX6_PCIE_FLAG_HAS_CLK_INBOUND_AXI)) {
> >  		ret = clk_prepare_enable(imx6_pcie->pcie_inbound_axi);
> > -		if (ret) {
> > -			dev_err(dev, "unable to enable pcie_axi clock\n");
> > -			break;
> > -		}
> > +		if (ret)
> > +			return ret;
> > +	}
> >  
> > +	if (imx6_check_flag(imx6_pcie, IMX6_PCIE_FLAG_HAS_CLK_AUX)) {
> > +		ret = clk_prepare_enable(imx6_pcie->pcie_aux);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	switch (imx6_pcie->drvdata->variant) {
> > +	case IMX6SX:
> >  		regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
> >  				   IMX6SX_GPR12_PCIE_TEST_POWERDOWN, 0);
> >  		break;
> > @@ -589,12 +597,6 @@ static int imx6_pcie_enable_ref_clk(struct imx6_pcie *imx6_pcie)
> >  	case IMX8MQ_EP:
> >  	case IMX8MP:
> >  	case IMX8MP_EP:
> > -		ret = clk_prepare_enable(imx6_pcie->pcie_aux);
> > -		if (ret) {
> > -			dev_err(dev, "unable to enable pcie_aux clock\n");
> > -			break;
> > -		}
> > -
> >  		offset = imx6_pcie_grp_offset(imx6_pcie);
> >  		/*
> >  		 * Set the over ride low and enabled
> > @@ -614,10 +616,13 @@ static int imx6_pcie_enable_ref_clk(struct imx6_pcie *imx6_pcie)
> >  
> >  static void imx6_pcie_disable_ref_clk(struct imx6_pcie *imx6_pcie)
> >  {
> > -	switch (imx6_pcie->drvdata->variant) {
> > -	case IMX6SX:
> > +	if (imx6_check_flag(imx6_pcie, IMX6_PCIE_FLAG_HAS_CLK_INBOUND_AXI))
> >  		clk_disable_unprepare(imx6_pcie->pcie_inbound_axi);
> > -		break;
> > +
> > +	if (imx6_check_flag(imx6_pcie, IMX6_PCIE_FLAG_HAS_CLK_AUX))
> > +		clk_disable_unprepare(imx6_pcie->pcie_aux);
> > +
> > +	switch (imx6_pcie->drvdata->variant) {
> >  	case IMX6QP:
> >  	case IMX6Q:
> >  		regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
> > @@ -631,14 +636,6 @@ static void imx6_pcie_disable_ref_clk(struct imx6_pcie *imx6_pcie)
> >  				   IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
> >  				   IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
> >  		break;
> > -	case IMX8MM:
> > -	case IMX8MM_EP:
> > -	case IMX8MQ:
> > -	case IMX8MQ_EP:
> > -	case IMX8MP:
> > -	case IMX8MP_EP:
> > -		clk_disable_unprepare(imx6_pcie->pcie_aux);
> > -		break;
> >  	default:
> >  		break;
> >  	}
> > @@ -1316,21 +1313,21 @@ static int imx6_pcie_probe(struct platform_device *pdev)
> >  		return dev_err_probe(dev, PTR_ERR(imx6_pcie->pcie),
> >  				     "pcie clock source missing or invalid\n");
> >  
> > -	switch (imx6_pcie->drvdata->variant) {
> > -	case IMX6SX:
> > -		imx6_pcie->pcie_inbound_axi = devm_clk_get(dev,
> > -							   "pcie_inbound_axi");
> > +	if (imx6_check_flag(imx6_pcie, IMX6_PCIE_FLAG_HAS_CLK_INBOUND_AXI)) {
> > +		imx6_pcie->pcie_inbound_axi = devm_clk_get(dev, "pcie_inbound_axi");
> >  		if (IS_ERR(imx6_pcie->pcie_inbound_axi))
> > -			return dev_err_probe(dev, PTR_ERR(imx6_pcie->pcie_inbound_axi),
> > -					     "pcie_inbound_axi clock missing or invalid\n");
> > -		break;
> > -	case IMX8MQ:
> > -	case IMX8MQ_EP:
> > +			dev_err_probe(dev, PTR_ERR(imx6_pcie->pcie_inbound_axi),
> > +				      "pcie_inbound_axi clock missing or invalid\n");
> > +	}
> > +
> > +	if (imx6_check_flag(imx6_pcie, IMX6_PCIE_FLAG_HAS_CLK_AUX)) {
> >  		imx6_pcie->pcie_aux = devm_clk_get(dev, "pcie_aux");
> >  		if (IS_ERR(imx6_pcie->pcie_aux))
> >  			return dev_err_probe(dev, PTR_ERR(imx6_pcie->pcie_aux),
> >  					     "pcie_aux clock source missing or invalid\n");
> > -		fallthrough;
> > +	}
> > +
> > +	switch (imx6_pcie->drvdata->variant) {
> >  	case IMX7D:
> >  		if (dbi_base->start == IMX8MQ_PCIE2_BASE_ADDR)
> >  			imx6_pcie->controller_id = 1;
> > @@ -1353,10 +1350,6 @@ static int imx6_pcie_probe(struct platform_device *pdev)
> >  	case IMX8MM_EP:
> >  	case IMX8MP:
> >  	case IMX8MP_EP:
> > -		imx6_pcie->pcie_aux = devm_clk_get(dev, "pcie_aux");
> > -		if (IS_ERR(imx6_pcie->pcie_aux))
> > -			return dev_err_probe(dev, PTR_ERR(imx6_pcie->pcie_aux),
> > -					     "pcie_aux clock source missing or invalid\n");
> >  		imx6_pcie->apps_reset = devm_reset_control_get_exclusive(dev,
> >  									 "apps");
> >  		if (IS_ERR(imx6_pcie->apps_reset))
> > @@ -1482,7 +1475,8 @@ static const struct imx6_pcie_drvdata drvdata[] = {
> >  		.variant = IMX6SX,
> >  		.flags = IMX6_PCIE_FLAG_IMX6_PHY |
> >  			 IMX6_PCIE_FLAG_IMX6_SPEED_CHANGE |
> > -			 IMX6_PCIE_FLAG_SUPPORTS_SUSPEND,
> > +			 IMX6_PCIE_FLAG_SUPPORTS_SUSPEND |
> > +			 IMX6_PCIE_FLAG_HAS_CLK_INBOUND_AXI,
> >  		.gpr = "fsl,imx6q-iomuxc-gpr",
> >  	},
> >  	[IMX6QP] = {
> > @@ -1500,30 +1494,36 @@ static const struct imx6_pcie_drvdata drvdata[] = {
> >  	},
> >  	[IMX8MQ] = {
> >  		.variant = IMX8MQ,
> > +		.flags = IMX6_PCIE_FLAG_HAS_CLK_AUX,
> >  		.gpr = "fsl,imx8mq-iomuxc-gpr",
> >  	},
> >  	[IMX8MM] = {
> >  		.variant = IMX8MM,
> > -		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND,
> > +		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND |
> > +			 IMX6_PCIE_FLAG_HAS_CLK_AUX,
> >  		.gpr = "fsl,imx8mm-iomuxc-gpr",
> >  	},
> >  	[IMX8MP] = {
> >  		.variant = IMX8MP,
> > -		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND,
> > +		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND |
> > +			 IMX6_PCIE_FLAG_HAS_CLK_AUX,
> >  		.gpr = "fsl,imx8mp-iomuxc-gpr",
> >  	},
> >  	[IMX8MQ_EP] = {
> >  		.variant = IMX8MQ_EP,
> > +		.flags = IMX6_PCIE_FLAG_HAS_CLK_AUX,
> >  		.mode = DW_PCIE_EP_TYPE,
> >  		.gpr = "fsl,imx8mq-iomuxc-gpr",
> >  	},
> >  	[IMX8MM_EP] = {
> >  		.variant = IMX8MM_EP,
> > +		.flags = IMX6_PCIE_FLAG_HAS_CLK_AUX,
> >  		.mode = DW_PCIE_EP_TYPE,
> >  		.gpr = "fsl,imx8mm-iomuxc-gpr",
> >  	},
> >  	[IMX8MP_EP] = {
> >  		.variant = IMX8MP_EP,
> > +		.flags = IMX6_PCIE_FLAG_HAS_CLK_AUX,
> >  		.mode = DW_PCIE_EP_TYPE,
> >  		.gpr = "fsl,imx8mp-iomuxc-gpr",
> >  	},
> > -- 
> > 2.34.1
> > 
> 
> -- 
> மணிவண்ணன் சதாசிவம்

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