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.

Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
---
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

On Fri, Aug 02, 2024 at 10:03:58AM +0200, Pawel Dembicki wrote:
> 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.
> 
> Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
> ---
> This patch came from net-next series[0].
> Changes since net-next:
>   - rebased to netdev/main only

Since this is targeting net, a fixes tag would still be good. If
nothing else it prevents somebody trying to backport it to linux
2.6.39 :-)

       Andrew

On 8/2/24 01:03, Pawel Dembicki wrote:
> 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.
> 
> Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian

On Fri, Aug 2, 2024 at 10:04 AM Pawel Dembicki <paweldembicki@gmail.com> wrote:

> 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.
>
> Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>

Good catch!
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij