Re: [PATCH RFC net-next 05/12] net: dsa: bcm_sf2: convert to phylink_generic_validate()

From: Tom Lendacky <thomas.lendacky@amd.com>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Heiner Kallweit <hkallweit1@gmail.com>
Cc: Vivien Didelot <vivien.didelot@gmail.com>,
	Vladimir Oltean <olteanv@gmail.com>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Claudiu Manoil <claudiu.manoil@nxp.com>,
	George McCollister <george.mccollister@gmail.com>,
	Hauke Mehrtens <hauke@hauke-m.de>,
	Kurt Kanzenbach <kurt@linutronix.de>,
	Vladimir Oltean <vladimir.oltean@nxp.com>,
	Woojung Huh <woojung.huh@microchip.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	netdev@vger.kernel.org, UNGLinuxDriver@microchip.com
Subject: Re: [PATCH RFC net-next 05/12] net: dsa: bcm_sf2: convert to phylink_generic_validate()
Date: Mon, 6 Dec 2021 09:59:46 -0600	[thread overview]
Message-ID: <24f210a9-54c9-eb0b-af88-a7ad75ce26aa@amd.com> (raw)
In-Reply-To: <YauArR7bd6Xh4ISt@shell.armlinux.org.uk>

On 12/4/21 8:52 AM, Russell King (Oracle) wrote:
> On Sat, Dec 04, 2021 at 08:59:12AM +0000, Russell King (Oracle) wrote:
>> On Fri, Dec 03, 2021 at 08:18:22PM -0800, Florian Fainelli wrote:

> 
> Here's a patch for one of my suggestions above. Tom, I'd appreciate
> if you could look at this please. Thanks.

I think it's fine to move the setting down. The driver that I was working 
on at the time only advertised 1000baseKX_Full for 1gpbs (which wasn't in 
the array and why I added it), so I don't see an issue with moving it down.

A quick build and test showed that I was able to successfully connect at 1 
gbps. I didn't dive any deeper than that.

Thanks,
Tom

> 
> 8<===
> From: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>
> Subject: [PATCH net-next] net: phy: prefer 1000baseT over 1000baseKX
> 
> The PHY settings table is supposed to be sorted by descending match
> priority - in other words, earlier entries are preferred over later
> entries.
> 
> The order of 1000baseKX/Full and 1000baseT/Full is such that we
> prefer 1000baseKX/Full over 1000baseT/Full, but 1000baseKX/Full is
> a lot rarer than 1000baseT/Full, and thus is much less likely to
> be preferred.
> 
> This causes phylink problems - it means a fixed link specifying a
> speed of 1G and full duplex gets an ethtool linkmode of 1000baseKX/Full
> rather than 1000baseT/Full as would be expected - and since we offer
> userspace a software emulation of a conventional copper PHY, we want
> to offer copper modes in preference to anything else. However, we do
> still want to allow the rarer modes as well.
> 
> Hence, let's reorder these two modes to prefer copper.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> ---
>   drivers/net/phy/phy-core.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
> index 2870c33b8975..271fc01f7f7f 100644
> --- a/drivers/net/phy/phy-core.c
> +++ b/drivers/net/phy/phy-core.c
> @@ -162,11 +162,11 @@ static const struct phy_setting settings[] = {
>   	PHY_SETTING(   2500, FULL,   2500baseT_Full		),
>   	PHY_SETTING(   2500, FULL,   2500baseX_Full		),
>   	/* 1G */
> -	PHY_SETTING(   1000, FULL,   1000baseKX_Full		),
>   	PHY_SETTING(   1000, FULL,   1000baseT_Full		),
>   	PHY_SETTING(   1000, HALF,   1000baseT_Half		),
>   	PHY_SETTING(   1000, FULL,   1000baseT1_Full		),
>   	PHY_SETTING(   1000, FULL,   1000baseX_Full		),
> +	PHY_SETTING(   1000, FULL,   1000baseKX_Full		),
>   	/* 100M */
>   	PHY_SETTING(    100, FULL,    100baseT_Full		),
>   	PHY_SETTING(    100, FULL,    100baseT1_Full		),
> 