linux-kernel - Re: [PATCH 1/3] PCI: layerscape: add function pointer for exit_from

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Message-ID: <20231016164036.GE39962@thinkpad>
Date:   Mon, 16 Oct 2023 22:10:36 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Frank Li <Frank.Li@....com>
Cc:     Minghuan Lian <minghuan.Lian@....com>,
        Mingkai Hu <mingkai.hu@....com>, Roy Zang <roy.zang@....com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "open list:PCI DRIVER FOR FREESCALE LAYERSCAPE" 
        <linuxppc-dev@...ts.ozlabs.org>,
        "open list:PCI DRIVER FOR FREESCALE LAYERSCAPE" 
        <linux-pci@...r.kernel.org>,
        "moderated list:PCI DRIVER FOR FREESCALE LAYERSCAPE" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>, imx@...ts.linux.dev
Subject: Re: [PATCH 1/3] PCI: layerscape: add function pointer for
 exit_from_l2()

On Fri, Sep 15, 2023 at 02:43:04PM -0400, Frank Li wrote:
> Difference layerscape chip have not difference exit_from_l2() method.
> Using function pointer for ls1028. It prepare for other layerscape
> suspend/resume support.
> 

How about:

Since difference SoCs require different sequence for exiting L2, let's add a
separate "exit_from_l2()" callback. This callback can be used to execute SoC
specific sequence.

> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
>  drivers/pci/controller/dwc/pci-layerscape.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
> index b931d597656f6..20c48c06e2248 100644
> --- a/drivers/pci/controller/dwc/pci-layerscape.c
> +++ b/drivers/pci/controller/dwc/pci-layerscape.c
> @@ -39,6 +39,8 @@
>  
>  struct ls_pcie_drvdata {
>  	const u32 pf_off;
> +	const struct dw_pcie_host_ops *ops;

Where is this ops used? If this is added as a preparatory for next patches, I'd
suggest you to move it to the respective one instead to avoid confusion.

> +	void (*exit_from_l2)(struct dw_pcie_rp *pp);
>  	bool pm_support;
>  };
>  
> @@ -180,6 +182,7 @@ static const struct ls_pcie_drvdata ls1021a_drvdata = {
>  static const struct ls_pcie_drvdata layerscape_drvdata = {
>  	.pf_off = 0xc0000,
>  	.pm_support = true,
> +	.exit_from_l2 = ls_pcie_exit_from_l2,
>  };
>  
>  static const struct of_device_id ls_pcie_of_match[] = {
> @@ -213,7 +216,7 @@ static int ls_pcie_probe(struct platform_device *pdev)
>  	pcie->drvdata = of_device_get_match_data(dev);
>  
>  	pci->dev = dev;
> -	pci->pp.ops = &ls_pcie_host_ops;
> +	pci->pp.ops = pcie->drvdata->ops ? pcie->drvdata->ops : &ls_pcie_host_ops;

This one also.

>  
>  	pcie->pci = pci;
>  
> @@ -251,7 +254,7 @@ static int ls_pcie_resume_noirq(struct device *dev)
>  	if (!pcie->drvdata->pm_support)
>  		return 0;
>  
> -	ls_pcie_exit_from_l2(&pcie->pci->pp);
> +	pcie->drvdata->exit_from_l2(&pcie->pci->pp);

You should always check for the existence of the callback first before invoking
it.

- Mani

>  
>  	return dw_pcie_resume_noirq(pcie->pci);
>  }
> -- 
> 2.34.1
> 

-- 
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