6.6-stable review patch. If anyone has any objections, please let me know.
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From: Enguerrand de Ribaucourt enguerrand.de-ribaucourt@savoirfairelinux.com
[ Upstream commit d963c95bc9840d070a788c35e41b715a648717f7 ]
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 Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/dsa/microchip/ksz9477.c | 4 ++++ drivers/net/dsa/microchip/ksz9477_reg.h | 1 + 2 files changed, 5 insertions(+)
diff --git a/drivers/net/dsa/microchip/ksz9477.c b/drivers/net/dsa/microchip/ksz9477.c index 353c41e031f1a..a7e8fcdf25768 100644 --- a/drivers/net/dsa/microchip/ksz9477.c +++ b/drivers/net/dsa/microchip/ksz9477.c @@ -1112,6 +1112,10 @@ 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 cba3dba58bc37..a2ef4b18349c4 100644 --- a/drivers/net/dsa/microchip/ksz9477_reg.h +++ b/drivers/net/dsa/microchip/ksz9477_reg.h @@ -267,6 +267,7 @@ #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)