Linux-PHY Archive on lore.kernel.org

* Re: [PATCH] phy: rockchip: naneng-combphy: configure SSC for PCIe on rk3588 and rk3576
From: Shawn Lin @ 2026-03-04 13:47 UTC (permalink / raw)
  To: Vinod Koul, linux-rockchip
  Cc: shawn.lin, linux-phy, Heiko Stuebner, Neil Armstrong,
	linux-kernel
In-Reply-To: <1772619211-99875-1-git-send-email-shawn.lin@rock-chips.com>

在 2026/03/04 星期三 18:13, Shawn Lin 写道:
> Add a dedicated function rk_combphy_cfg_ssc_for_pcie() to configure
> Spread Spectrum Clocking (SSC) for the PCIe PHY on compatible platforms.
> 
> The function first checks the device tree node's compatible string.
> Currently, SSC tuning is specifically implemented and applied only for
> "rockchip,rk3588-naneng-combphy" and "rockchip,rk3576-naneng-combphy".
> 

Sorry, I amended the patch in the last minute before sending it which
seems not able to work after re-testing. Will update v2.

> The correct SSC configuration for these platforms involves:
> 1.  Enabling SSC via the RK3568_PHYREG8_SSC_EN bit.
> 2.  Setting the PLL SSC module control via the newly defined
>      RK3568_PHYREG33_PLL_SSC_CTRL bit.
> 3.  For PCIe phys with a 24MHz reference clock, additional PLL loop
>      divider and signal adjustment values are programmed to optimiz
>      performance.
> 
> This SSC configuration is intended to improve EMI characteristics or
> meet specific clock tolerance requirements for PCIe interfaces on
> these SoCs.
> 
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
> ---
> 
>   drivers/phy/rockchip/phy-rockchip-naneng-combphy.c | 93 +++++++++++++---------
>   1 file changed, 55 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/phy/rockchip/phy-rockchip-naneng-combphy.c b/drivers/phy/rockchip/phy-rockchip-naneng-combphy.c
> index b60d6bf..aa09d71 100644
> --- a/drivers/phy/rockchip/phy-rockchip-naneng-combphy.c
> +++ b/drivers/phy/rockchip/phy-rockchip-naneng-combphy.c
> @@ -121,6 +121,7 @@
>   #define RK3568_PHYREG32_SSC_OFFSET_500PPM	1
>   
>   #define RK3568_PHYREG33				0x80
> +#define RK3568_PHYREG33_PLL_SSC_CTRL		BIT(5)
>   #define RK3568_PHYREG33_PLL_KVCO_MASK		GENMASK(4, 2)
>   #define RK3568_PHYREG33_PLL_KVCO_SHIFT		2
>   #define RK3568_PHYREG33_PLL_KVCO_VALUE		2
> @@ -964,6 +965,56 @@ static const struct rockchip_combphy_cfg rk3568_combphy_cfgs = {
>   	.combphy_cfg	= rk3568_combphy_cfg,
>   };
>   
> +static void rk_combphy_cfg_ssc_for_pcie(struct rockchip_combphy_priv *priv, unsigned long rate)
> +{
> +	struct device_node *np = priv->dev->of_node;
> +	u32 val;
> +
> +	/* Some SoCs' combphys share the same PCIe SSC tuning result */
> +	if (!of_device_is_compatible(np, "rockchip,rk3588-naneng-combphy") ||
> +	    !of_device_is_compatible(np, "rockchip,rk3576-naneng-combphy")) {
> +		dev_warn(priv->dev, "Incompatible platform\n");
> +		return;
> +	}
> +
> +	val = readl(priv->mmio + RK3568_PHYREG8);
> +	val |= RK3568_PHYREG8_SSC_EN;
> +	writel(val, priv->mmio + RK3568_PHYREG8);
> +
> +	/* PLL control SSC module period should be set */
> +	val = readl(priv->mmio + RK3568_PHYREG33);
> +	val |= RK3568_PHYREG33_PLL_SSC_CTRL;
> +	writel(val, priv->mmio + RK3568_PHYREG33);
> +
> +	if (priv->type == PHY_TYPE_PCIE && rate == REF_CLOCK_24MHz) {
> +		/* Set PLL loop divider */
> +		writel(0x00, priv->mmio + RK3576_PHYREG17);
> +		writel(RK3568_PHYREG18_PLL_LOOP, priv->mmio + RK3568_PHYREG18);
> +
> +		/* Set up rx_pck invert and rx msb to disable */
> +		writel(0x00, priv->mmio + RK3588_PHYREG27);
> +
> +		/*
> +		 * Set up SU adjust signal:
> +		 * su_trim[7:0],   PLL KVCO adjust bits[2:0] to min
> +		 * su_trim[15:8],  PLL LPF R1 adujst bits[9:7]=3'b101
> +		 * su_trim[23:16], CKRCV adjust
> +		 * su_trim[31:24], CKDRV adjust
> +		 */
> +		writel(0x90, priv->mmio + RK3568_PHYREG11);
> +		writel(0x02, priv->mmio + RK3568_PHYREG12);
> +		writel(0x08, priv->mmio + RK3568_PHYREG13);
> +		writel(0x57, priv->mmio + RK3568_PHYREG14);
> +		writel(0x40, priv->mmio + RK3568_PHYREG15);
> +
> +		writel(RK3568_PHYREG16_SSC_CNT_VALUE, priv->mmio + RK3568_PHYREG16);
> +
> +		val = FIELD_PREP(RK3568_PHYREG33_PLL_KVCO_MASK,
> +				 RK3576_PHYREG33_PLL_KVCO_VALUE);
> +		writel(val, priv->mmio + RK3568_PHYREG33);
> +	}
> +}
> +
>   static int rk3576_combphy_cfg(struct rockchip_combphy_priv *priv)
>   {
>   	const struct rockchip_combphy_grfcfg *cfg = priv->cfg->grfcfg;
> @@ -1156,39 +1207,8 @@ static int rk3576_combphy_cfg(struct rockchip_combphy_priv *priv)
>   		}
>   	}
>   
> -	if (priv->enable_ssc) {
> -		val = readl(priv->mmio + RK3568_PHYREG8);
> -		val |= RK3568_PHYREG8_SSC_EN;
> -		writel(val, priv->mmio + RK3568_PHYREG8);
> -
> -		if (priv->type == PHY_TYPE_PCIE && rate == REF_CLOCK_24MHz) {
> -			/* Set PLL loop divider */
> -			writel(0x00, priv->mmio + RK3576_PHYREG17);
> -			writel(RK3568_PHYREG18_PLL_LOOP, priv->mmio + RK3568_PHYREG18);
> -
> -			/* Set up rx_pck invert and rx msb to disable */
> -			writel(0x00, priv->mmio + RK3588_PHYREG27);
> -
> -			/*
> -			 * Set up SU adjust signal:
> -			 * su_trim[7:0],   PLL KVCO adjust bits[2:0] to min
> -			 * su_trim[15:8],  PLL LPF R1 adujst bits[9:7]=3'b101
> -			 * su_trim[23:16], CKRCV adjust
> -			 * su_trim[31:24], CKDRV adjust
> -			 */
> -			writel(0x90, priv->mmio + RK3568_PHYREG11);
> -			writel(0x02, priv->mmio + RK3568_PHYREG12);
> -			writel(0x08, priv->mmio + RK3568_PHYREG13);
> -			writel(0x57, priv->mmio + RK3568_PHYREG14);
> -			writel(0x40, priv->mmio + RK3568_PHYREG15);
> -
> -			writel(RK3568_PHYREG16_SSC_CNT_VALUE, priv->mmio + RK3568_PHYREG16);
> -
> -			val = FIELD_PREP(RK3568_PHYREG33_PLL_KVCO_MASK,
> -					 RK3576_PHYREG33_PLL_KVCO_VALUE);
> -			writel(val, priv->mmio + RK3568_PHYREG33);
> -		}
> -	}
> +	if (priv->enable_ssc)
> +		rk_combphy_cfg_ssc_for_pcie(priv, rate);
>   
>   	return 0;
>   }
> @@ -1371,11 +1391,8 @@ static int rk3588_combphy_cfg(struct rockchip_combphy_priv *priv)
>   		}
>   	}
>   
> -	if (priv->enable_ssc) {
> -		val = readl(priv->mmio + RK3568_PHYREG8);
> -		val |= RK3568_PHYREG8_SSC_EN;
> -		writel(val, priv->mmio + RK3568_PHYREG8);
> -	}
> +	if (priv->enable_ssc)
> +		rk_combphy_cfg_ssc_for_pcie(priv, rate);
>   
>   	return 0;
>   }
> 

-- 
linux-phy mailing list
linux-phy@lists.infradead.org
https://lists.infradead.org/mailman/listinfo/linux-phy

^ permalink raw reply