linux-kernel - Re: [PATCH V1 8/9] phy: tegra: p2u: Set ENABLE_L2_EXIT_RATE

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Message-ID: <YylZnfan61xlXFWb@matsya>
Date:   Tue, 20 Sep 2022 11:41:41 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Vidya Sagar <vidyas@...dia.com>
Cc:     lpieralisi@...nel.org, robh@...nel.org, kw@...ux.com,
        bhelgaas@...gle.com, thierry.reding@...il.com,
        jonathanh@...dia.com, kishon@...com, mani@...nel.org,
        Sergey.Semin@...kalelectronics.ru, ffclaire1224@...il.com,
        linux-pci@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-phy@...ts.infradead.org,
        kthota@...dia.com, mmaddireddy@...dia.com, sagar.tv@...il.com
Subject: Re: [PATCH V1 8/9] phy: tegra: p2u: Set ENABLE_L2_EXIT_RATE_CHANGE
 in calibration

On 19-09-22, 20:06, Vidya Sagar wrote:
> Set ENABLE_L2_EXIT_RATE_CHANGE to request UPHY PLL rate change to Gen1
> during initialization. This helps in the below surprise down cases,
>   - Surprise down happens at Gen3/Gen4 link speed
>   - Surprise down happens and external REFCLK is cut off which causes
> UPHY PLL rate to deviate to an invalid rate
> 
> ENABLE_L2_EXIT_RATE_CHANGE needs to be set to bring the UPHY PLL rate
> back to Gen1 during controller initialization for the link up.
> 
> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
> ---
>  drivers/phy/tegra/phy-tegra194-p2u.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/phy/tegra/phy-tegra194-p2u.c b/drivers/phy/tegra/phy-tegra194-p2u.c
> index 1415ca71de38..fb710e89acac 100644
> --- a/drivers/phy/tegra/phy-tegra194-p2u.c
> +++ b/drivers/phy/tegra/phy-tegra194-p2u.c
> @@ -15,6 +15,7 @@
>  #include <linux/phy/phy.h>
>  
>  #define P2U_CONTROL_CMN			0x74
> +#define P2U_CONTROL_CMN_ENABLE_L2_EXIT_RATE_CHANGE		BIT(13)
>  #define P2U_CONTROL_CMN_SKP_SIZE_PROTECTION_EN			BIT(20)
>  
>  #define P2U_PERIODIC_EQ_CTRL_GEN3	0xc0
> @@ -85,8 +86,21 @@ static int tegra_p2u_power_on(struct phy *x)
>  	return 0;
>  }
>  
> +int tegra_p2u_calibrate(struct phy *x)

why not static?

> +{
> +	struct tegra_p2u *phy = phy_get_drvdata(x);
> +	u32 val;
> +
> +	val = p2u_readl(phy, P2U_CONTROL_CMN);
> +	val |= P2U_CONTROL_CMN_ENABLE_L2_EXIT_RATE_CHANGE;
> +	p2u_writel(phy, val, P2U_CONTROL_CMN);
> +
> +	return 0;
> +}
> +
>  static const struct phy_ops ops = {
>  	.power_on = tegra_p2u_power_on,
> +	.calibrate = tegra_p2u_calibrate,
>  	.owner = THIS_MODULE,
>  };
>  
> -- 
> 2.17.1

-- 
~Vinod