netdev - Re: [PATCH RFC] net: bgmac: improve handling PHY

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Date:   Tue, 21 Sep 2021 11:40:30 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Rafał Miłecki <zajec5@...il.com>,
        netdev@...r.kernel.org
Cc:     devicetree@...r.kernel.org, bcm-kernel-feedback-list@...adcom.com,
        Andrew Lunn <andrew@...n.ch>,
        Vladimir Oltean <olteanv@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Saravana Kannan <saravanak@...gle.com>,
        Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH RFC] net: bgmac: improve handling PHY

On 9/21/21 5:02 AM, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@...ecki.pl>
> 
> 1. Use info from DT if available
> 
> It allows describing for example a fixed link. It's more accurate than
> just guessing there may be one (depending on a chipset).
> 
> 2. Verify PHY ID before trying to connect PHY
> 
> PHY addr 0x1e (30) is special in Broadcom routers and means a switch
> connected as MDIO devices instead of a real PHY. Don't try connecting to
> it.
> 
> Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>

Yes this does appear to be a better strategy, you would want to put that
in the same patch set that adds support for the "mdio" node container to
avoid regressions, thanks!

> ---
>  drivers/net/ethernet/broadcom/bgmac-bcma.c | 33 ++++++++++++++--------
>  1 file changed, 21 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/net/ethernet/broadcom/bgmac-bcma.c b/drivers/net/ethernet/broadcom/bgmac-bcma.c
> index 85fa0ab7201c..e39361042aa1 100644
> --- a/drivers/net/ethernet/broadcom/bgmac-bcma.c
> +++ b/drivers/net/ethernet/broadcom/bgmac-bcma.c
> @@ -11,6 +11,7 @@
>  #include <linux/bcma/bcma.h>
>  #include <linux/brcmphy.h>
>  #include <linux/etherdevice.h>
> +#include <linux/of_mdio.h>
>  #include <linux/of_net.h>
>  #include "bgmac.h"
>  
> @@ -86,17 +87,28 @@ static int bcma_phy_connect(struct bgmac *bgmac)
>  	struct phy_device *phy_dev;
>  	char bus_id[MII_BUS_ID_SIZE + 3];
>  
> +	/* DT info should be the most accurate */
> +	phy_dev = of_phy_get_and_connect(bgmac->net_dev, bgmac->dev->of_node,
> +					 bgmac_adjust_link);
> +	if (phy_dev)
> +		return 0;
> +
>  	/* Connect to the PHY */
> -	snprintf(bus_id, sizeof(bus_id), PHY_ID_FMT, bgmac->mii_bus->id,
> -		 bgmac->phyaddr);
> -	phy_dev = phy_connect(bgmac->net_dev, bus_id, bgmac_adjust_link,
> -			      PHY_INTERFACE_MODE_MII);
> -	if (IS_ERR(phy_dev)) {
> -		dev_err(bgmac->dev, "PHY connection failed\n");
> -		return PTR_ERR(phy_dev);
> +	if (bgmac->mii_bus && bgmac->phyaddr != BGMAC_PHY_NOREGS) {
> +		snprintf(bus_id, sizeof(bus_id), PHY_ID_FMT, bgmac->mii_bus->id,
> +			 bgmac->phyaddr);
> +		phy_dev = phy_connect(bgmac->net_dev, bus_id, bgmac_adjust_link,
> +				      PHY_INTERFACE_MODE_MII);
> +		if (IS_ERR(phy_dev)) {
> +			dev_err(bgmac->dev, "PHY connection failed\n");
> +			return PTR_ERR(phy_dev);
> +		}
> +
> +		return 0;
>  	}
>  
> -	return 0;
> +	/* Assume a fixed link to the switch port */
> +	return bgmac_phy_connect_direct(bgmac);
>  }
>  
>  static const struct bcma_device_id bgmac_bcma_tbl[] = {
> @@ -295,10 +307,7 @@ static int bgmac_probe(struct bcma_device *core)
>  	bgmac->cco_ctl_maskset = bcma_bgmac_cco_ctl_maskset;
>  	bgmac->get_bus_clock = bcma_bgmac_get_bus_clock;
>  	bgmac->cmn_maskset32 = bcma_bgmac_cmn_maskset32;
> -	if (bgmac->mii_bus)
> -		bgmac->phy_connect = bcma_phy_connect;
> -	else
> -		bgmac->phy_connect = bgmac_phy_connect_direct;
> +	bgmac->phy_connect = bcma_phy_connect;
>  
>  	err = bgmac_enet_probe(bgmac);
>  	if (err)
> 


-- 
Florian