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;
}
