linux-kernel - Re: [PATCH V7 2/3] PCI: dwc: Cleanup DBI,ATU read and write APIs

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Message-ID: <PSXP216MB0662E297AC662E53D515141CAAE10@PSXP216MB0662.KORP216.PROD.OUTLOOK.COM>
Date:   Sun, 23 Jun 2019 07:47:09 +0000
From:   Jingoo Han <jingoohan1@...il.com>
To:     Vidya Sagar <vidyas@...dia.com>,
        "gustavo.pimentel@...opsys.com" <gustavo.pimentel@...opsys.com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "Jisheng.Zhang@...aptics.com" <Jisheng.Zhang@...aptics.com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "kishon@...com" <kishon@...com>
CC:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kthota@...dia.com" <kthota@...dia.com>,
        "mmaddireddy@...dia.com" <mmaddireddy@...dia.com>,
        "sagar.tv@...il.com" <sagar.tv@...il.com>,
        Han Jingoo <jingoohan1@...il.com>
Subject: Re: [PATCH V7 2/3] PCI: dwc: Cleanup DBI,ATU read and write APIs

On 6/23/19, 1:52 AM, Vidya Sagar wrote:
>
> Cleanup DBI read and write APIs by removing "__" (underscore) from their
> names as there are no no-underscore versions and the underscore versions
> are already doing what no-underscore versions typically do. It also removes
> passing dbi/dbi2 base address as one of the arguments as the same can be
> derived with in read and write APIs. Since dw_pcie_{readl/writel}_dbi()
> APIs can't be used for ATU read/write as ATU base address could be
> different from DBI base address, this patch attempts to implement
> ATU read/write APIs using ATU base address without using
> dw_pcie_{readl/writel}_dbi() APIs.
>
> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
> ---
> Changes from v6:
> * Modified ATU read/write APIs to use implementation specific DBI read/write
>   APIs if present.
>
> Changes from v5:
> * Removed passing base address as one of the arguments as the same can be derived within
>   the API itself.
> * Modified ATU read/write APIs to call dw_pcie_{write/read}() API
>
> Changes from v4:
> * This is a new patch in this series
>
>  drivers/pci/controller/dwc/pcie-designware.c | 28 +++++------
>  drivers/pci/controller/dwc/pcie-designware.h | 51 +++++++++++++-------
>  2 files changed, 45 insertions(+), 34 deletions(-)

.....

>  static inline void dw_pcie_writel_atu(struct dw_pcie *pci, u32 reg, u32 val)
>  {
> -	__dw_pcie_write_dbi(pci, pci->atu_base, reg, 0x4, val);
> +	int ret;
> +
> +	if (pci->ops->write_dbi) {
> +		pci->ops->write_dbi(pci, pci->atu_base, reg, 0x4, val);
> +		return;
> +	}
> +
> +	ret = dw_pcie_write(pci->atu_base + reg, 0x4, val);
> +	if (ret)
> +		dev_err(pci->dev, "Write ATU address failed\n");
>  }
>  
>  static inline u32 dw_pcie_readl_atu(struct dw_pcie *pci, u32 reg)
>  {
> -	return __dw_pcie_read_dbi(pci, pci->atu_base, reg, 0x4);
> +	int ret;
> +	u32 val;
> +
> +	if (pci->ops->read_dbi)
> +		return pci->ops->read_dbi(pci, pci->atu_base, reg, 0x4);
> +
> +	ret = dw_pcie_read(pci->atu_base + reg, 0x4, &val);
> +	if (ret)
> +		dev_err(pci->dev, "Read ATU address failed\n");
> +
> +	return val;
>  }

Hmm. In cases of dbi and  dbi2, readb/readw/readl and writeb/writew/writel are
located in pcie-designware.h. These functions just call read/write which are located
in pcie-designware.c. For readability, would you write the code as below?

1. For drivers/pci/controller/dwc/pcie-designware.h,
    Just call dw_pcie_{write/read}_atu(), instead of implementing functions as below.

	static inline void dw_pcie_writel_atu(struct dw_pcie *pci, u32 reg, u32 val)
	{
		return  dw_pcie_write_atu(pci, reg, 0x4, val);
	}

	static inline u32 dw_pcie_readl_atu(struct dw_pcie *pci, u32 reg)	
	{
		return  dw_pcie_read_atu(pci, reg, 0x4);
	}

2. For drivers/pci/controller/dwc/pcie-designware.c,
    Please add new dw_pcie_{write/read}_atu() as below.

	void dw_pcie_write_atu(struct dw_pcie *pci, u32 reg, size_t size, u32 val)
	{
		int ret;

		if (pci->ops->write_dbi) {
			pci->ops->write_dbi(pci, pci->atu_base, reg, size, val);
			return;
		}

		ret = dw_pcie_write(pci->atu_base + reg, size, val);
		if (ret)
			dev_err(pci->dev, "Write ATU address failed\n");
	}

	u32 dw_pcie_read_atu(struct dw_pcie *pci, u32 reg, size_t size)
	{
		int ret;
		u32 val;

		if (pci->ops->read_dbi)
			return pci->ops->read_dbi(pci, pci->atu_base, reg, size);

		ret = dw_pcie_read(pci->atu_base + reg, size, &val);
		if (ret)
			dev_err(pci->dev, "Read ATU address failed\n");

		return val;
	}

Thank you.

Best regards,
Jingoo Han

>  
>  static inline void dw_pcie_dbi_ro_wr_en(struct dw_pcie *pci)
> -- 
> 2.17.1