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Message-ID: <2cdc67aa-6029-7231-76a8-54c6b51b066c@gmail.com>
Date:   Fri, 11 Aug 2023 08:07:03 +0200
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To:     Luke Lu <luke.lu@libre.computer>, Andrew Lunn <andrew@lunn.ch>,
        Russell King <linux@armlinux.org.uk>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Kevin Hilman <khilman@baylibre.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Florian Fainelli <f.fainelli@gmail.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
        Da Xue <da@libre.computer>
References: <20230809214946.18975-1-luke.lu@libre.computer>
Content-Language: en-US
From:   Heiner Kallweit <hkallweit1@gmail.com>
Subject: Re: [PATCH net v4] net: phy: meson-gxl: implement
 meson_gxl_phy_resume()
In-Reply-To: <20230809214946.18975-1-luke.lu@libre.computer>
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On 09.08.2023 23:49, Luke Lu wrote:
> From: Da Xue <da@libre.computer>
> 
> While testing the suspend/resume function, we found the ethernet
> is broken if using internal PHY of Amlogic meson GXL SoC.
> After system resume back, the ethernet is down, no carrier found.
> 
> 	eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state
> 		DOWN group default qlen 1000
> 
> In this patch, we re-initialize the internal PHY to fix this problem.
> 

It's not an unusual case that system cuts power to the PHY during
system suspend. So the PHY needs to be re-initialized on resume.
That's why we call phy_init_hw() in mdio_bus_phy_resume().

If going your way we would be better off calling .config_init()
in genphy_resume(). Please check the MAC driver, maybe it's better
to re-initialize the PHY in the resume path of the MAC driver.

> 	eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP
> 		group default qlen 1000
> 
> Fixes: 7334b3e47aee ("net: phy: Add Meson GXL Internal PHY driver")
> Signed-off-by: Da Xue <da@libre.computer>
> Signed-off-by: Luke Lu <luke.lu@libre.computer>
> 
> ---
> Note, we don't Cc stable kernel tree in this patch intentionally, since
> there will be a cherry-pick failure if apply this patch from kernel version
> less than v6.2, it's not a logic failure but due to the changes too close.
> 
> Please check commit 69ff53e4a4c9 ("net: phy: meson-gxl: use MMD access dummy stubs for GXL, internal PHY")
> We plan to slightly rework the patch, and send it to stable tree separately
> once this patch is accepted into mainline.
> 
> v4:
>  - refactor commit message to better explain the problem & fix
>  - check return value of genphy_resume()
>  - add 'net' annotation
>  - add Fixes tag
> 
> v3: https://lore.kernel.org/netdev/20230808050016.1911447-1-da@libre.computer
>  - fix missing parameter of genphy_resume()
> 
> v2: https://lore.kernel.org/netdev/20230804201903.1303713-1-da@libre.computer
>  - call generic genphy_resume()
> 
> v1: https://lore.kernel.org/all/CACqvRUZRyXTVQyy9bUviQZ+_moLQBjPc6nin_NQC+CJ37yNnLw@mail.gmail.com
> ---
>  drivers/net/phy/meson-gxl.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/meson-gxl.c b/drivers/net/phy/meson-gxl.c
> index bb9b33b6bce2..9ebe09b0cd8c 100644
> --- a/drivers/net/phy/meson-gxl.c
> +++ b/drivers/net/phy/meson-gxl.c
> @@ -132,6 +132,21 @@ static int meson_gxl_config_init(struct phy_device *phydev)
>  	return 0;
>  }
>  
> +static int meson_gxl_phy_resume(struct phy_device *phydev)
> +{
> +	int ret;
> +
> +	ret = genphy_resume(phydev);
> +	if (ret)
> +		return ret;
> +
> +	ret = meson_gxl_config_init(phydev);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
>  /* This function is provided to cope with the possible failures of this phy
>   * during aneg process. When aneg fails, the PHY reports that aneg is done
>   * but the value found in MII_LPA is wrong:
> @@ -196,7 +211,7 @@ static struct phy_driver meson_gxl_phy[] = {
>  		.config_intr	= smsc_phy_config_intr,
>  		.handle_interrupt = smsc_phy_handle_interrupt,
>  		.suspend        = genphy_suspend,
> -		.resume         = genphy_resume,
> +		.resume         = meson_gxl_phy_resume,
>  		.read_mmd	= genphy_read_mmd_unsupported,
>  		.write_mmd	= genphy_write_mmd_unsupported,
>  	}, {