linux-kernel - Re: [PATCH v4 3/3] PCI: dw-rockchip: Unify link status checks with FIELD

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Message-ID: <40232d5ef59383dc44fd8b91dbc2b0ba71f1d84f.camel@gmail.com>
Date: Mon, 28 Apr 2025 13:26:54 +1000
From: Wilfred Mallawa <wilfred.opensource@...il.com>
To: Hans Zhang <18255117159@....com>, lpieralisi@...nel.org, kw@...ux.com, 
	bhelgaas@...gle.com, heiko@...ech.de
Cc: manivannan.sadhasivam@...aro.org, robh@...nel.org, jingoohan1@...il.com,
 	shawn.lin@...k-chips.com, linux-pci@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-rockchip@...ts.infradead.org, Niklas Cassel <cassel@...nel.org>
Subject: Re: [PATCH v4 3/3] PCI: dw-rockchip: Unify link status checks with
 FIELD_GET

On Sun, 2025-04-27 at 20:53 +0800, Hans Zhang wrote:
> Link-up detection manually checked PCIE_LINKUP bits across RC/EP
> modes,
> leading to code duplication. Centralize the logic using FIELD_GET.
> This
> removes redundancy and abstracts hardware-specific bit masking,
> ensuring
> consistent link state handling.
> 
> Signed-off-by: Hans Zhang <18255117159@....com>
> Reviewed-by: Niklas Cassel <cassel@...nel.org>
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  drivers/pci/controller/dwc/pcie-dw-rockchip.c | 21 +++++++----------
> --
>  1 file changed, 8 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
> b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
> index a778f4f61595..bfc47dab32e5 100644
> --- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
> +++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
> @@ -8,6 +8,7 @@
>   * Author: Simon Xue <xxm@...k-chips.com>
>   */
>  
> +#include <linux/bitfield.h>
>  #include <linux/clk.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/irqchip/chained_irq.h>
> @@ -60,9 +61,8 @@
>  
>  /* LTSSM Status Register */
>  #define PCIE_CLIENT_LTSSM_STATUS	0x300
> -#define  PCIE_SMLH_LINKUP		BIT(16)
> -#define  PCIE_RDLH_LINKUP		BIT(17)
> -#define  PCIE_LINKUP			(PCIE_SMLH_LINKUP |
> PCIE_RDLH_LINKUP)
> +#define  PCIE_LINKUP			0x3
> +#define  PCIE_LINKUP_MASK		GENMASK(17, 16)
>  #define  PCIE_LTSSM_STATUS_MASK		GENMASK(5, 0)
>  
>  struct rockchip_pcie {
> @@ -188,10 +188,7 @@ static int rockchip_pcie_link_up(struct dw_pcie
> *pci)
>  	struct rockchip_pcie *rockchip = to_rockchip_pcie(pci);
>  	u32 val = rockchip_pcie_get_ltssm(rockchip);
>  
> -	if ((val & PCIE_LINKUP) == PCIE_LINKUP)
> -		return 1;
> -
> -	return 0;
> +	return FIELD_GET(PCIE_LINKUP_MASK, val) == PCIE_LINKUP;
>  }
>  
>  static void rockchip_pcie_enable_l0s(struct dw_pcie *pci)
> @@ -450,7 +447,7 @@ static irqreturn_t
> rockchip_pcie_rc_sys_irq_thread(int irq, void *arg)
>  	struct dw_pcie *pci = &rockchip->pci;
>  	struct dw_pcie_rp *pp = &pci->pp;
>  	struct device *dev = pci->dev;
> -	u32 reg, val;
> +	u32 reg;
>  
>  	reg = rockchip_pcie_readl_apb(rockchip,
> PCIE_CLIENT_INTR_STATUS_MISC);
>  	rockchip_pcie_writel_apb(rockchip, reg,
> PCIE_CLIENT_INTR_STATUS_MISC);
> @@ -459,8 +456,7 @@ static irqreturn_t
> rockchip_pcie_rc_sys_irq_thread(int irq, void *arg)
>  	dev_dbg(dev, "LTSSM_STATUS: %#x\n",
> rockchip_pcie_get_ltssm(rockchip));
>  
>  	if (reg & PCIE_RDLH_LINK_UP_CHGED) {
> -		val = rockchip_pcie_get_ltssm(rockchip);
> -		if ((val & PCIE_LINKUP) == PCIE_LINKUP) {
> +		if (rockchip_pcie_link_up(pci)) {
>  			dev_dbg(dev, "Received Link up event.
> Starting enumeration!\n");
>  			/* Rescan the bus to enumerate endpoint
> devices */
>  			pci_lock_rescan_remove();
> @@ -477,7 +473,7 @@ static irqreturn_t
> rockchip_pcie_ep_sys_irq_thread(int irq, void *arg)
>  	struct rockchip_pcie *rockchip = arg;
>  	struct dw_pcie *pci = &rockchip->pci;
>  	struct device *dev = pci->dev;
> -	u32 reg, val;
> +	u32 reg;
>  
>  	reg = rockchip_pcie_readl_apb(rockchip,
> PCIE_CLIENT_INTR_STATUS_MISC);
>  	rockchip_pcie_writel_apb(rockchip, reg,
> PCIE_CLIENT_INTR_STATUS_MISC);
> @@ -491,8 +487,7 @@ static irqreturn_t
> rockchip_pcie_ep_sys_irq_thread(int irq, void *arg)
>  	}
>  
>  	if (reg & PCIE_RDLH_LINK_UP_CHGED) {
> -		val = rockchip_pcie_get_ltssm(rockchip);
> -		if ((val & PCIE_LINKUP) == PCIE_LINKUP) {
> +		if (rockchip_pcie_link_up(pci)) {
>  			dev_dbg(dev, "link up\n");
>  			dw_pcie_ep_linkup(&pci->ep);
>  		}

Reviewed-by: Wilfred Mallawa <wilfred.mallawa@....com>