linux-kernel - Re: [PATCH RESEND v3 07/10] PCI: visconti: Convert to using generic resources getter

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Message-ID: <20230411111947.GI5333@thinkpad>
Date:   Tue, 11 Apr 2023 16:49:47 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>, g@...nkpad
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Cai Huoqing <cai.huoqing@...ux.dev>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Vinod Koul <vkoul@...nel.org>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Rob Herring <robh@...nel.org>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@...hiba.co.jp>,
        Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        linux-pci@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org, Bjorn Helgaas <helgaas@...nel.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH RESEND v3 07/10] PCI: visconti: Convert to using generic
 resources getter

On Tue, Apr 11, 2023 at 06:39:25AM +0300, Serge Semin wrote:
> The generic resources request infrastructure has been recently added to
> the DW PCIe core driver. Since the DT-bindings of the Toshibo Visconti
> PCIe Host controller is fully compatible with the generic names set let's
> convert the driver to using that infrastructure. It won't take much effort
> since the low-level device driver implies the resources request only with
> no additional manipulations involving them. So just drop the locally
> defined clocks request procedures, activate the generic resources request
> capability and make sure the mandatory resources have been requested by
> the DW PCIe core driver.
> 
> Suggested-by: Bjorn Helgaas <helgaas@...nel.org>
> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> ---
>  drivers/pci/controller/dwc/pcie-visconti.c | 37 ++++++++++------------
>  1 file changed, 17 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-visconti.c b/drivers/pci/controller/dwc/pcie-visconti.c
> index 71026fefa366..ae1517b52c58 100644
> --- a/drivers/pci/controller/dwc/pcie-visconti.c
> +++ b/drivers/pci/controller/dwc/pcie-visconti.c
> @@ -29,9 +29,6 @@ struct visconti_pcie {
>  	void __iomem *ulreg_base;
>  	void __iomem *smu_base;
>  	void __iomem *mpu_base;
> -	struct clk *refclk;
> -	struct clk *coreclk;
> -	struct clk *auxclk;
>  };
>  
>  #define PCIE_UL_REG_S_PCIE_MODE		0x00F4
> @@ -198,6 +195,21 @@ static int visconti_pcie_host_init(struct dw_pcie_rp *pp)
>  	int err;
>  	u32 val;
>  
> +	if (!pcie->pci.core_clks[DW_PCIE_REF_CLK].clk) {
> +		dev_err(pci->dev, "Missing ref clock source\n");
> +		return -ENOENT;
> +	}
> +
> +	if (!pcie->pci.core_clks[DW_PCIE_CORE_CLK].clk) {
> +		dev_err(pci->dev, "Missing core clock source\n");
> +		return -ENOENT;
> +	}
> +
> +	if (!pcie->pci.core_clks[DW_PCIE_AUX_CLK].clk) {
> +		dev_err(pci->dev, "Missing aux clock source\n");
> +		return -ENOENT;
> +	}
> +

Looking at the driver, I could see no call to clk_prepare_enable() for these
clocks. So from kernel's PoV these are not used at all. So either these clocks
are not required (unlikely) or enabled by the bootloader so kernel just uses it.

In that case, the driver should handle these clocks properly.

@Nobuhiro-San, can you please comment?

- Mani

>  	visconti_smu_writel(pcie,
>  			    PISMU_CKON_PCIE_AUX_CLK | PISMU_CKON_PCIE_MSTR_ACLK,
>  			    PISMU_CKON_PCIE);
> @@ -242,8 +254,6 @@ static const struct dw_pcie_host_ops visconti_pcie_host_ops = {
>  static int visconti_get_resources(struct platform_device *pdev,
>  				  struct visconti_pcie *pcie)
>  {
> -	struct device *dev = &pdev->dev;
> -
>  	pcie->ulreg_base = devm_platform_ioremap_resource_byname(pdev, "ulreg");
>  	if (IS_ERR(pcie->ulreg_base))
>  		return PTR_ERR(pcie->ulreg_base);
> @@ -256,21 +266,6 @@ static int visconti_get_resources(struct platform_device *pdev,
>  	if (IS_ERR(pcie->mpu_base))
>  		return PTR_ERR(pcie->mpu_base);
>  
> -	pcie->refclk = devm_clk_get(dev, "ref");
> -	if (IS_ERR(pcie->refclk))
> -		return dev_err_probe(dev, PTR_ERR(pcie->refclk),
> -				     "Failed to get ref clock\n");
> -
> -	pcie->coreclk = devm_clk_get(dev, "core");
> -	if (IS_ERR(pcie->coreclk))
> -		return dev_err_probe(dev, PTR_ERR(pcie->coreclk),
> -				     "Failed to get core clock\n");
> -
> -	pcie->auxclk = devm_clk_get(dev, "aux");
> -	if (IS_ERR(pcie->auxclk))
> -		return dev_err_probe(dev, PTR_ERR(pcie->auxclk),
> -				     "Failed to get aux clock\n");
> -
>  	return 0;
>  }
>  
> @@ -304,6 +299,8 @@ static int visconti_pcie_probe(struct platform_device *pdev)
>  	pci->dev = dev;
>  	pci->ops = &dw_pcie_ops;
>  
> +	dw_pcie_cap_set(pci, REQ_RES);
> +
>  	ret = visconti_get_resources(pdev, pcie);
>  	if (ret)
>  		return ret;
> -- 
> 2.40.0
> 
> 

-- 
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