From: Javen Xu <javen_xu@realsil.com.cn>

Firmware execution routine unconditionally uses phy_modify_mmd() for
all OP_WRITE entries which introduces an unnecessary read transaction
when updating an entire 16-bit register. So we optimize this by
checking bitmask boundaries. Use phy_write_mmd() directly to speed up
firmware loading process.

Benchmark number from tracing MDC/MDIO hardware transactions during
firmware loading process:
 - Unpatched: about 28,000 MDIO transactions
 - Patched: about 9,600 MDIO transactions
This results in an approx 65% reduction in MDIO traffic.

Signed-off-by: Javen Xu <javen_xu@realsil.com.cn>
---
 drivers/net/phy/realtek/realtek_main.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/realtek/realtek_main.c b/drivers/net/phy/realtek/realtek_main.c
index 27e31a799e2c..97b0b67b9900 100644
--- a/drivers/net/phy/realtek/realtek_main.c
+++ b/drivers/net/phy/realtek/realtek_main.c
@@ -548,8 +548,12 @@ static int rtl8261x_fw_execute_entry(struct phy_device *phydev,
 
 	switch (entry->type) {
 	case OP_WRITE:
-		ret = phy_modify_mmd(phydev, dev, addr,
-				     GENMASK(msb, lsb), (value << lsb) & GENMASK(msb, lsb));
+		if (msb != 15 || lsb != 0)
+			ret = phy_modify_mmd(phydev, dev, addr, GENMASK(msb, lsb),
+					     (value << lsb) & GENMASK(msb, lsb));
+		else
+			ret = phy_write_mmd(phydev, dev, addr, value);
+
 		if (ret)
 			return ret;
 		break;
-- 
2.43.0

On Fri, Sep 11, 2026 at 05:45:27PM +0800, javen wrote:
> From: Javen Xu <javen_xu@realsil.com.cn>
> 
> Firmware execution routine unconditionally uses phy_modify_mmd() for
> all OP_WRITE entries which introduces an unnecessary read transaction
> when updating an entire 16-bit register. So we optimize this by
> checking bitmask boundaries. Use phy_write_mmd() directly to speed up
> firmware loading process.
> 
> Benchmark number from tracing MDC/MDIO hardware transactions during
> firmware loading process:
>  - Unpatched: about 28,000 MDIO transactions
>  - Patched: about 9,600 MDIO transactions
> This results in an approx 65% reduction in MDIO traffic.
> 
> Signed-off-by: Javen Xu <javen_xu@realsil.com.cn>

Thanks for the numbers.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

On 11.9.2026 11:45, javen wrote:
> From: Javen Xu <javen_xu@realsil.com.cn>
> 
> Firmware execution routine unconditionally uses phy_modify_mmd() for
> all OP_WRITE entries which introduces an unnecessary read transaction
> when updating an entire 16-bit register. So we optimize this by
> checking bitmask boundaries. Use phy_write_mmd() directly to speed up
> firmware loading process.
> 
> Benchmark number from tracing MDC/MDIO hardware transactions during
> firmware loading process:
>  - Unpatched: about 28,000 MDIO transactions
>  - Patched: about 9,600 MDIO transactions
> This results in an approx 65% reduction in MDIO traffic.
> 
> Signed-off-by: Javen Xu <javen_xu@realsil.com.cn>
> ---
>  drivers/net/phy/realtek/realtek_main.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/phy/realtek/realtek_main.c 
> b/drivers/net/phy/realtek/realtek_main.c
> index 27e31a799e2c..97b0b67b9900 100644
> --- a/drivers/net/phy/realtek/realtek_main.c
> +++ b/drivers/net/phy/realtek/realtek_main.c
> @@ -548,8 +548,12 @@ static int rtl8261x_fw_execute_entry(struct 
> phy_device *phydev,
> 
>  	switch (entry->type) {
>  	case OP_WRITE:
> -		ret = phy_modify_mmd(phydev, dev, addr,
> -				     GENMASK(msb, lsb), (value << lsb) & GENMASK(msb, lsb));
> +		if (msb != 15 || lsb != 0)
> +			ret = phy_modify_mmd(phydev, dev, addr, GENMASK(msb, lsb),
> +					     (value << lsb) & GENMASK(msb, lsb));
> +		else
> +			ret = phy_write_mmd(phydev, dev, addr, value);
> +
>  		if (ret)
>  			return ret;
>  		break;

Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>

Thanks,
Nicolai