linux-kernel - Re: [PATCH v6 04/10] PCI: imx6: Introduce SoC specific callbacks for controlling REFCLK

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Message-ID: <20240630160404.GA5264@thinkpad>
Date: Sun, 30 Jun 2024 21:34:04 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Frank Li <Frank.Li@....com>
Cc: Richard Zhu <hongxing.zhu@....com>,
	Lucas Stach <l.stach@...gutronix.de>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	NXP Linux Team <linux-imx@....com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-pci@...r.kernel.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v6 04/10] PCI: imx6: Introduce SoC specific callbacks for
 controlling REFCLK

On Mon, Jun 17, 2024 at 04:16:40PM -0400, Frank Li wrote:
> Instead of using the switch case statement to enable/disable the reference
> clock handled by this driver itself, let's introduce a new callback
> set_ref_clk() and define it for platforms that require it. This simplifies

Should this be called 'enable_ref_clk' since the callback is supposed to enable
REFCLK?

> the code.
> 
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 112 ++++++++++++++++------------------
>  1 file changed, 52 insertions(+), 60 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 47134e2dfecf2..ff9d0098294fa 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -103,6 +103,7 @@ struct imx_pcie_drvdata {
>  	const u32 mode_mask[IMX_PCIE_MAX_INSTANCES];
>  	const struct pci_epc_features *epc_features;
>  	int (*init_phy)(struct imx_pcie *pcie);
> +	int (*set_ref_clk)(struct imx_pcie *pcie, bool enable);
>  };
>  
>  struct imx_pcie {
> @@ -585,21 +586,19 @@ static int imx_pcie_attach_pd(struct device *dev)
>  	return 0;
>  }
>  
> -static int imx_pcie_enable_ref_clk(struct imx_pcie *imx_pcie)
> +static int imx6sx_pcie_set_ref_clk(struct imx_pcie *imx_pcie, bool enable)
>  {
> -	unsigned int offset;
> -	int ret = 0;
> +	regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12, IMX6SX_GPR12_PCIE_TEST_POWERDOWN,
> +			   enable ? 0 : IMX6SX_GPR12_PCIE_TEST_POWERDOWN);
>  
> -	switch (imx_pcie->drvdata->variant) {
> -	case IMX6SX:
> -		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
> -				   IMX6SX_GPR12_PCIE_TEST_POWERDOWN, 0);
> -		break;
> -	case IMX6QP:
> -	case IMX6Q:
> +	return 0;
> +}
> +
> +static int imx6q_pcie_set_ref_clk(struct imx_pcie *imx_pcie, bool enable)
> +{
> +	if (enable) {
>  		/* power up core phy and enable ref clock */
> -		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1,
> -				   IMX6Q_GPR1_PCIE_TEST_PD, 0 << 18);
> +		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1, IMX6Q_GPR1_PCIE_TEST_PD, 0);
>  		/*
>  		 * the async reset input need ref clock to sync internally,
>  		 * when the ref clock comes after reset, internal synced
> @@ -608,54 +607,34 @@ static int imx_pcie_enable_ref_clk(struct imx_pcie *imx_pcie)
>  		 */
>  		usleep_range(10, 100);
>  		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1,
> -				   IMX6Q_GPR1_PCIE_REF_CLK_EN, 1 << 16);
> -		break;
> -	case IMX7D:
> -	case IMX95:
> -	case IMX95_EP:
> -		break;
> -	case IMX8MM:
> -	case IMX8MM_EP:
> -	case IMX8MQ:
> -	case IMX8MQ_EP:
> -	case IMX8MP:
> -	case IMX8MP_EP:
> -		offset = imx_pcie_grp_offset(imx_pcie);
> -		/*
> -		 * Set the over ride low and enabled
> -		 * make sure that REF_CLK is turned on.
> -		 */
> -		regmap_update_bits(imx_pcie->iomuxc_gpr, offset,
> -				   IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE,
> -				   0);
> -		regmap_update_bits(imx_pcie->iomuxc_gpr, offset,
> -				   IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE_EN,
> -				   IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE_EN);
> -		break;
> +				   IMX6Q_GPR1_PCIE_REF_CLK_EN, IMX6Q_GPR1_PCIE_REF_CLK_EN);
> +	} else {
> +		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1,
> +				   IMX6Q_GPR1_PCIE_REF_CLK_EN, 0);
> +		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1,
> +				   IMX6Q_GPR1_PCIE_TEST_PD, IMX6Q_GPR1_PCIE_TEST_PD);
>  	}
>  
> -	return ret;
> +	return 0;
>  }
>  
> -static void imx_pcie_disable_ref_clk(struct imx_pcie *imx_pcie)
> +static int imx8mm_pcie_set_ref_clk(struct imx_pcie *imx_pcie, bool enable)
>  {
> -	switch (imx_pcie->drvdata->variant) {
> -	case IMX6QP:
> -	case IMX6Q:
> -		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1,
> -				IMX6Q_GPR1_PCIE_REF_CLK_EN, 0);
> -		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1,
> -				IMX6Q_GPR1_PCIE_TEST_PD,
> -				IMX6Q_GPR1_PCIE_TEST_PD);
> -		break;
> -	case IMX7D:
> -		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
> -				   IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
> -				   IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
> -		break;
> -	default:
> -		break;
> -	}
> +	int offset = imx_pcie_grp_offset(imx_pcie);
> +
> +	/* Set the over ride low and enabled make sure that REF_CLK is turned on.*/

This comment provides no useful info. So please remove it.

> +	regmap_update_bits(imx_pcie->iomuxc_gpr, offset, IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE,
> +			   enable ? 0 : IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE);
> +	regmap_update_bits(imx_pcie->iomuxc_gpr, offset, IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE_EN,
> +			   enable ? IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE_EN : 0);
> +	return 0;
> +}
> +
> +static int imx7d_pcie_set_ref_clk(struct imx_pcie *imx_pcie, bool enable)
> +{
> +	regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12, IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
> +			    enable ? 0 : IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
> +	return 0;

Previously imx6_pcie_enable_ref_clk() was bailing out for IMX7D. But now you are
explicitly enabling it. What is the reason?

- Mani

-- 
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