Re: [PATCH net-next 2/5] net: phy: realtek: simplify C22 reg access via MDIO_MMD_VEND2
From: Heiner Kallweit <hkallweit1@gmail.com>
Date: 2026-01-09 07:27:43
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On 1/9/2026 4:03 AM, Daniel Golle wrote:
RealTek 2.5GE PHYs have all standard Clause-22 registers mapped also inside MDIO_MMD_VEND2 at offset 0xa400. This is used mainly in case the PHY is inside a copper SFP module which uses the RollBall MDIO-over-I2C method which *only* supports Clause-45. In order to support such modules, the PHY driver has previously been split into a C22-only and C45-only instances, creating quite a bit of redundancy and confusion.
To complement: RTL812x MAC/PHY chips allow access to MDIO_MMD_VEND2 of the integrated PHY only. There is no native C22 MDIO access.
quoted hunk ↗ jump to hunk
In preparation of reunifying the two driver instances, add support for translating MDIO_MMD_VEND2 registers 0xa400 to 0xa438 back to standard Clause-22 access in case the PHY is accessed on a Clause-22 bus. Signed-off-by: Daniel Golle <daniel@makrotopia.org> --- drivers/net/phy/realtek/realtek_main.c | 11 +++++++++++ 1 file changed, 11 insertions(+)diff --git a/drivers/net/phy/realtek/realtek_main.c b/drivers/net/phy/realtek/realtek_main.c index 7302b25b8908b..886694ff995f6 100644 --- a/drivers/net/phy/realtek/realtek_main.c +++ b/drivers/net/phy/realtek/realtek_main.c@@ -143,6 +143,7 @@ #define RTL822X_VND2_TO_PAGE(reg) ((reg) >> 4) #define RTL822X_VND2_TO_PAGE_REG(reg) (16 + (((reg) & GENMASK(3, 0)) >> 1)) +#define RTL822X_VND2_TO_C22_REG(reg) (((reg) - 0xa400) / 2) #define RTL822X_VND2_C22_REG(reg) (0xa400 + 2 * (reg)) #define RTL8221B_VND2_INER 0xa4d2@@ -1264,6 +1265,11 @@ static int rtl822xb_read_mmd(struct phy_device *phydev, int devnum, u16 reg) return mmd_phy_read(phydev->mdio.bus, phydev->mdio.addr, phydev->is_c45, devnum, reg); + /* Simplify access to C22-registers addressed inside MDIO_MMD_VEND2 */ + if (reg >= RTL822X_VND2_C22_REG(0) && + reg <= RTL822X_VND2_C22_REG(30)) + return __phy_read(phydev, RTL822X_VND2_TO_C22_REG(reg)); + /* Use paged access for MDIO_MMD_VEND2 over Clause-22 */ page = RTL822X_VND2_TO_PAGE(reg); oldpage = __phy_read(phydev, RTL821x_PAGE_SELECT);@@ -1299,6 +1305,11 @@ static int rtl822xb_write_mmd(struct phy_device *phydev, int devnum, u16 reg, return mmd_phy_write(phydev->mdio.bus, phydev->mdio.addr, phydev->is_c45, devnum, reg, val); + /* Simplify access to C22-registers addressed inside MDIO_MMD_VEND2 */ + if (reg >= RTL822X_VND2_C22_REG(0) && + reg <= RTL822X_VND2_C22_REG(30)) + return __phy_write(phydev, RTL822X_VND2_TO_C22_REG(reg), val); + /* Use paged access for MDIO_MMD_VEND2 over Clause-22 */ page = RTL822X_VND2_TO_PAGE(reg); oldpage = __phy_read(phydev, RTL821x_PAGE_SELECT);