Re: [PATCH v13 11/22] PCI: dwc: Add dw_pcie_link_set_max_width()

[Manivannan Sadhasivam <mani@kernel.org>]

On Tue, Apr 18, 2023 at 09:23:52PM +0900, Yoshihiro Shimoda wrote:
> To improve code readability, add dw_pcie_link_set_max_width().
> The original code writes the PCIE_PORT_LINK_CONTROL register twice
> if the pci->num_lanes is not zero. But, it should avoid to write
> the register twice. So, refactor it.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 65 ++++++++++----------
>  1 file changed, 34 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 69358dc202f0..c76fa78c6468 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -737,6 +737,39 @@ static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 link_gen)
>  	dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, cap | link_speed);
>  }
>  
> +static void dw_pcie_link_set_max_width(struct dw_pcie *pci, u32 num_lanes)
> +{
> +	u32 val;
> +
> +	/* Set the number of lanes */
> +	val = dw_pcie_readl_dbi(pci, PCIE_PORT_LINK_CONTROL);
> +	val &= ~PORT_LINK_FAST_LINK_MODE;
> +	val |= PORT_LINK_DLL_LINK_EN;
> +
> +	/* Mask LINK_MODE if num_lanes is not zero */
> +	if (num_lanes)
> +		val &= ~PORT_LINK_MODE_MASK;
> +
> +	switch (num_lanes) {
> +	case 1:
> +		val |= PORT_LINK_MODE_1_LANES;
> +		break;
> +	case 2:
> +		val |= PORT_LINK_MODE_2_LANES;
> +		break;
> +	case 4:
> +		val |= PORT_LINK_MODE_4_LANES;
> +		break;
> +	case 8:
> +		val |= PORT_LINK_MODE_8_LANES;
> +		break;
> +	default:
> +		dev_dbg(pci->dev, "Using h/w default number of lanes\n");
> +		return;

Here you are not updating the LINK_CONTROL register. You should break instead of
returning.

> +	}

Newline here.

- Mani

> +	dw_pcie_writel_dbi(pci, PCIE_PORT_LINK_CONTROL, val);
> +}
> +
>  static void dw_pcie_link_set_max_link_width(struct dw_pcie *pci, u32 num_lanes)
>  {
>  	u32 val;
> @@ -1040,36 +1073,6 @@ void dw_pcie_setup(struct dw_pcie *pci)
>  		dw_pcie_writel_dbi(pci, PCIE_PL_CHK_REG_CONTROL_STATUS, val);
>  	}
>  
> -	val = dw_pcie_readl_dbi(pci, PCIE_PORT_LINK_CONTROL);
> -	val &= ~PORT_LINK_FAST_LINK_MODE;
> -	val |= PORT_LINK_DLL_LINK_EN;
> -	dw_pcie_writel_dbi(pci, PCIE_PORT_LINK_CONTROL, val);
> -
> -	if (!pci->num_lanes) {
> -		dev_dbg(pci->dev, "Using h/w default number of lanes\n");
> -		return;
> -	}
> -
> -	/* Set the number of lanes */
> -	val &= ~PORT_LINK_MODE_MASK;
> -	switch (pci->num_lanes) {
> -	case 1:
> -		val |= PORT_LINK_MODE_1_LANES;
> -		break;
> -	case 2:
> -		val |= PORT_LINK_MODE_2_LANES;
> -		break;
> -	case 4:
> -		val |= PORT_LINK_MODE_4_LANES;
> -		break;
> -	case 8:
> -		val |= PORT_LINK_MODE_8_LANES;
> -		break;
> -	default:
> -		dev_err(pci->dev, "num-lanes %u: invalid value\n", pci->num_lanes);
> -		return;
> -	}
> -	dw_pcie_writel_dbi(pci, PCIE_PORT_LINK_CONTROL, val);
> -
> +	dw_pcie_link_set_max_width(pci, pci->num_lanes);
>  	dw_pcie_link_set_max_link_width(pci, pci->num_lanes);
>  }
> -- 
> 2.25.1
> 

-- 
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