Currently, phy_config() is invoked every time during am65_cpsw_start() which guarantees robustness and also allows recovering from link failures by resetting the Ethernet PHY. While this is beneficial for system stability, for use-cases where speed is prioritized over robustness, the existing implementation is insufficient.
To support use-cases prioritizing speed while continuing to retain the existing behavior for robustness, sample the environment variable named "am65_cpsw_phy_config_once" to determine whether phy_config() should continue to be invoked once per invocation of am65_cpsw_start(), OR, it should only be invoked across invocations. Since the environment variable is not set by default, robustness is prioritized over speed. Use-cases which require speed can set "am65_cpsw_phy_config_once" to any of: '1', 'y', 'Y', 't' and 'T' based on the implementation of the env_get_yesno() helper function. Signed-off-by: Siddharth Vadapalli <[email protected]> --- Hello, This patch is based on commit 3cdce049f90 erge tag 'u-boot-rockchip-20260610' of https://source.denx.de/u-boot/custodians/u-boot-rockchip of the master branch of U-Boot. Patch has been tested on J784S4 EVM which uses MCU CPSW2G for Ethernet functionality. The following test logs demonstrate the default behavior being retained in the absence of 'am65_cpsw_phy_config_once' environment variable being set to a logical true, followed by setting the environment variable to a logical true ('y') and observing the PHY Autonegotiation process being skipped, followed by setting the environment variable to a logical false ('n' but could be anything that isn't logically true based on the env_get_yesno() helper function) and verifying that we go back to the default behavior of performing PHY Autonegotiation again: https://gist.github.com/Siddharth-Vadapalli-at-TI/6229b5a3b7d80cd0c2037a6364406bbe Regards, Siddharth. drivers/net/ti/am65-cpsw-nuss.c | 32 +++++++++++++++++++++++++++----- 1 file changed, 27 insertions(+), 5 deletions(-) diff --git a/drivers/net/ti/am65-cpsw-nuss.c b/drivers/net/ti/am65-cpsw-nuss.c index 84a3e44ecbc..a5cca52f674 100644 --- a/drivers/net/ti/am65-cpsw-nuss.c +++ b/drivers/net/ti/am65-cpsw-nuss.c @@ -18,6 +18,7 @@ #include <dm/pinctrl.h> #include <dma-uclass.h> #include <dm/of_access.h> +#include <env.h> #include <miiphy.h> #include <net.h> #include <phy.h> @@ -104,6 +105,7 @@ struct am65_cpsw_port { fdt_addr_t macsl_base; bool disabled; u32 mac_control; + bool phy_configured; }; struct am65_cpsw_common { @@ -313,7 +315,7 @@ static int am65_cpsw_start(struct udevice *dev) struct am65_cpsw_port *port = &common->ports[priv->port_id]; struct am65_cpsw_port *port0 = &common->ports[0]; struct ti_udma_drv_chan_cfg_data *dma_rx_cfg_data; - int ret, i; + int ret, i, skip_phy_config_env; if (common->started) return 0; @@ -426,10 +428,30 @@ static int am65_cpsw_start(struct udevice *dev) port->port_sgmii_base + AM65_CPSW_SGMII_CONTROL_REG); } - ret = phy_config(priv->phydev); - if (ret < 0) { - dev_err(dev, "phy_config failed: %d", ret); - goto err_dis_rx; + /* + * Invoking phy_config() every time that am65_cpsw_start() is executed will + * make the link robust. However, it delays every networking command such as + * 'dhcp' and 'tftp'. For use-cases that prioritize speed over robustness, + * phy_config() should be invoked only once. To support both use-cases, + * sample the environment variable 'am65_cpsw_phy_config_once' to switch + * between: + * a) Invoke phy_config() every time - Default behavior for robustness + * b) Invoke phy_config() once per driver probe - User configurable behavior + * for speed. + */ + skip_phy_config_env = env_get_yesno("am65_cpsw_phy_config_once"); + + /* If environment variable is not defined, assume it to be false. */ + if (skip_phy_config_env == -1) + skip_phy_config_env = 0; + + if (!port->phy_configured || !skip_phy_config_env) { + ret = phy_config(priv->phydev); + if (ret < 0) { + dev_err(dev, "phy_config failed: %d", ret); + goto err_dis_rx; + } + port->phy_configured = true; } ret = phy_startup(priv->phydev); -- 2.51.1
