| Message ID | 20240614094642.122464-3-enguerrand.de-ribaucourt@savoirfairelinux.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Handle new Microchip KSZ 9897 Errata | expand |
On Fri, Jun 14, 2024 at 09:46:41AM +0000, Enguerrand de Ribaucourt wrote: > Errata DS80000758 states that carrier sense back pressure mode can cause > link down issues in 100BASE-TX half duplex mode. The datasheet also > recommends to always use the collision based back pressure mode. > > Fixes: b987e98e50ab ("dsa: add DSA switch driver for Microchip KSZ9477") > Signed-off-by: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@savoirfairelinux.com> > Reviewed-by: Woojung Huh <Woojung.huh@microchip.com> > Acked-by: Arun Ramadoss <arun.ramadoss@microchip.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Andrew
diff --git a/drivers/net/dsa/microchip/ksz9477.c b/drivers/net/dsa/microchip/ksz9477.c index f8ad7833f5d9..c2878dd0ad7e 100644 --- a/drivers/net/dsa/microchip/ksz9477.c +++ b/drivers/net/dsa/microchip/ksz9477.c @@ -1299,6 +1299,10 @@ int ksz9477_setup(struct dsa_switch *ds) /* Enable REG_SW_MTU__2 reg by setting SW_JUMBO_PACKET */ ksz_cfg(dev, REG_SW_MAC_CTRL_1, SW_JUMBO_PACKET, true); + /* Use collision based back pressure mode. */ + ksz_cfg(dev, REG_SW_MAC_CTRL_1, SW_BACK_PRESSURE, + SW_BACK_PRESSURE_COLLISION); + /* Now we can configure default MTU value */ ret = regmap_update_bits(ksz_regmap_16(dev), REG_SW_MTU__2, REG_SW_MTU_MASK, VLAN_ETH_FRAME_LEN + ETH_FCS_LEN); diff --git a/drivers/net/dsa/microchip/ksz9477_reg.h b/drivers/net/dsa/microchip/ksz9477_reg.h index f3a205ee483f..fb124be8edd3 100644 --- a/drivers/net/dsa/microchip/ksz9477_reg.h +++ b/drivers/net/dsa/microchip/ksz9477_reg.h @@ -247,6 +247,7 @@ #define REG_SW_MAC_CTRL_1 0x0331 #define SW_BACK_PRESSURE BIT(5) +#define SW_BACK_PRESSURE_COLLISION 0 #define FAIR_FLOW_CTRL BIT(4) #define NO_EXC_COLLISION_DROP BIT(3) #define SW_JUMBO_PACKET BIT(2)
Errata DS80000758 states that carrier sense back pressure mode can cause link down issues in 100BASE-TX half duplex mode. The datasheet also recommends to always use the collision based back pressure mode. Fixes: b987e98e50ab ("dsa: add DSA switch driver for Microchip KSZ9477") Signed-off-by: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@savoirfairelinux.com> Reviewed-by: Woojung Huh <Woojung.huh@microchip.com> Acked-by: Arun Ramadoss <arun.ramadoss@microchip.com> --- v5: - define SW_BACK_PRESSURE_COLLISION v4: https://lore.kernel.org/all/20240531142430.678198-5-enguerrand.de-ribaucourt@savoirfairelinux.com/ - rebase on net/main - add Fixes tag v3: https://lore.kernel.org/all/20240530102436.226189-5-enguerrand.de-ribaucourt@savoirfairelinux.com/ --- drivers/net/dsa/microchip/ksz9477.c | 4 ++++ drivers/net/dsa/microchip/ksz9477_reg.h | 1 + 2 files changed, 5 insertions(+)