[PATCH net v2 1/5] net: dsa: vsc73xx: fix port MAC configuration in full duplex mode

Pawel Dembicki
2024-08-05T21:11:01Z

According to the datasheet description ("Port Mode Procedure" in 5.6.2),
the VSC73XX_MAC_CFG_WEXC_DIS bit is configured only for half duplex mode.

The WEXC_DIS bit is responsible for MAC behavior after an excessive
collision. Let's set it as described in the datasheet.

Fixes: 05bd97fc559d ("net: dsa: Add Vitesse VSC73xx DSA router driver")
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
---
v2:
- Added 'Fixes' and 'Reviewed-by' to commit message.

This patch came from net-next series[0].
Changes since net-next:
- rebased to netdev/main only

[0] https://patchwork.kernel.org/project/netdevbpf/patch/20240729210615.279952-6-paweldembicki@gmail.com/
---
drivers/net/dsa/vitesse-vsc73xx-core.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/vitesse-vsc73xx-core.c b/drivers/net/dsa/vitesse-vsc73xx-core.c
index d9d3e30fd47a..f548ed4cb23f 100644
--- a/drivers/net/dsa/vitesse-vsc73xx-core.c
+++ b/drivers/net/dsa/vitesse-vsc73xx-core.c
@@ -957,6 +957,11 @@ static void vsc73xx_mac_link_up(struct phylink_config *config,

if (duplex == DUPLEX_FULL)
val |= VSC73XX_MAC_CFG_FDX;
+ else
+ /* In datasheet description ("Port Mode Procedure" in 5.6.2)
+ * this bit is configured only for half duplex.
+ */
+ val |= VSC73XX_MAC_CFG_WEXC_DIS;

/* This routine is described in the datasheet (below ARBDISC register
* description)
@@ -967,7 +972,6 @@ static void vsc73xx_mac_link_up(struct phylink_config *config,
get_random_bytes(&seed, 1);
val |= seed << VSC73XX_MAC_CFG_SEED_OFFSET;
val |= VSC73XX_MAC_CFG_SEED_LOAD;
- val |= VSC73XX_MAC_CFG_WEXC_DIS;

/* Those bits are responsible for MTU only. Kernel takes care about MTU,
* let's enable +8 bytes frame length unconditionally.
--
2.34.1