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Message-ID: <20240601171340.GU491852@kernel.org>
Date: Sat, 1 Jun 2024 18:13:40 +0100
From: Simon Horman <horms@...nel.org>
To: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@...oirfairelinux.com>
Cc: netdev@...r.kernel.org, andrew@...n.ch, hkallweit1@...il.com,
linux@...linux.org.uk, woojung.huh@...rochip.com,
UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH net v4 1/5] net: phy: micrel: add Microchip KSZ 9897
Switch PHY support
On Fri, May 31, 2024 at 02:24:26PM +0000, Enguerrand de Ribaucourt wrote:
> There is a DSA driver for microchip,ksz9897 which can be controlled
> through SPI or I2C. This patch adds support for it's CPU ports PHYs to
> also allow network access to the switch's CPU port.
>
> The CPU ports PHYs of the KSZ9897 are not documented in the datasheet.
> They weirdly use the same PHY ID as the KSZ8081, which is a different
> PHY and that driver isn't compatible with KSZ9897. Before this patch,
> the KSZ8081 driver was used for the CPU ports of the KSZ9897 but the
> link would never come up.
>
> A new driver for the KSZ9897 is added, based on the compatible KSZ87XX.
> I could not test if Gigabit Ethernet works, but the link comes up and
> can successfully allow packets to be sent and received with DSA tags.
>
> To resolve the KSZ8081/KSZ9897 phy_id conflicts, I could not find any
> stable register to distinguish them. Instead of a match_phy_device() ,
> I've declared a virtual phy_id with the highest value in Microchip's OUI
> range.
>
> Example usage in the device tree:
> compatible = "ethernet-phy-id0022.17ff";
>
> A discussion to find better alternatives had been opened with the
> Microchip team, with no response yet.
>
> See https://lore.kernel.org/all/20220207174532.362781-1-enguerrand.de-ribaucourt@savoirfairelinux.com/
>
> Fixes: b987e98e50ab ("dsa: add DSA switch driver for Microchip KSZ9477")
> Signed-off-by: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@...oirfairelinux.com>
...
> diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
...
> @@ -5495,6 +5495,17 @@ static struct phy_driver ksphy_driver[] = {
> .suspend = genphy_suspend,
> .resume = genphy_resume,
> .get_features = ksz9477_get_features,
> +}, {
> + .phy_id = PHY_ID_KSZ9897,
> + .phy_id_mask = MICREL_PHY_ID_MASK,
> + .name = "Microchip KSZ9897 Switch",
> + /* PHY_BASIC_FEATURES */
> + .config_init = kszphy_config_init,
> + .config_aneg = ksz8873mll_config_aneg,
> + .read_status = ksz8873mll_read_status,
> + /* No suspend/resume callbacks because of errata DS00002330D:
> + * Toggling PHY Powerdown can cause errors or link failures in adjacent PHYs
> + */
It looks like there will be another version of this patchset.
If so, please line-wrap the comment above so it is 80 columns wide or less,
as is preferred for Networking code.
Likewise in the following patch.
Flagged by checkpatch.pl --max-line-length=80
> } };
>
> module_phy_driver(ksphy_driver);
...
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