Message-ID: <1be1444c-b1f7-b7d6-adaa-78960c381161@gmail.com>
Date:   Mon, 10 Jan 2022 09:34:03 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.4.1
Content-Language: en-US
To:     Mohammad Athari Bin Ismail <mohammad.athari.ismail@intel.com>,
        Andrew Lunn <andrew@lunn.ch>,
        "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Oleksij Rempel <linux@rempel-privat.de>,
        Russell King <linux@armlinux.org.uk>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org
References: <20220110062117.17540-1-mohammad.athari.ismail@intel.com>
 <20220110062117.17540-2-mohammad.athari.ismail@intel.com>
From:   Heiner Kallweit <hkallweit1@gmail.com>
Subject: Re: [PATCH net 1/1] net: phy: marvell: add Marvell specific PHY
 loopback
In-Reply-To: <20220110062117.17540-2-mohammad.athari.ismail@intel.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 10.01.2022 07:21, Mohammad Athari Bin Ismail wrote:
> Existing genphy_loopback() is not applicable for Marvell PHY. So,
> adding Marvell specific PHY loopback operation by only setting(enable) or
> clearing(disable) BMCR_LOOPBACK bit.
> 
> Tested working on Marvell 88E1510.
> 
With this change you'd basically revert the original change and loose
its functionality. Did you check the Marvell datasheets?
At least for few versions I found that you may have to configure
bits 0..2 in MAC Specific Control Register 2 (page 2, register 21)
instead of BMCR.


> Fixes: 014068dcb5b1 ("net: phy: genphy_loopback: add link speed configuration")
> Cc: <stable@vger.kernel.org> # 5.15.x
> Signed-off-by: Mohammad Athari Bin Ismail <mohammad.athari.ismail@intel.com>
> ---
>  drivers/net/phy/marvell.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c
> index 4fcfca4e1702..2a73a959b48b 100644
> --- a/drivers/net/phy/marvell.c
> +++ b/drivers/net/phy/marvell.c
> @@ -1932,6 +1932,12 @@ static void marvell_get_stats(struct phy_device *phydev,
>  		data[i] = marvell_get_stat(phydev, i);
>  }
>  
> +static int marvell_loopback(struct phy_device *phydev, bool enable)
> +{
> +	return phy_modify(phydev, MII_BMCR, BMCR_LOOPBACK,
> +			  enable ? BMCR_LOOPBACK : 0);
> +}
> +
>  static int marvell_vct5_wait_complete(struct phy_device *phydev)
>  {
>  	int i;
> @@ -3078,7 +3084,7 @@ static struct phy_driver marvell_drivers[] = {
>  		.get_sset_count = marvell_get_sset_count,
>  		.get_strings = marvell_get_strings,
>  		.get_stats = marvell_get_stats,
> -		.set_loopback = genphy_loopback,
> +		.set_loopback = marvell_loopback,
>  		.get_tunable = m88e1011_get_tunable,
>  		.set_tunable = m88e1011_set_tunable,
>  		.cable_test_start = marvell_vct7_cable_test_start,