6.12-stable review patch. If anyone has any objections, please let me know.
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From: Aksh Garg a-garg7@ti.com
[ Upstream commit d4b00d132d7cb70a74bc039c91c1d6120943c71b ]
The am65_cpsw_iet_verify_wait() function attempts verification 20 times, toggling the AM65_CPSW_PN_IET_MAC_LINKFAIL bit in each iteration. When the LINKFAIL bit transitions from 1 to 0, the MAC merge layer initiates the verification process and waits for the timeout configured in MAC_VERIFY_CNT before automatically retransmitting. The MAC_VERIFY_CNT register is configured according to the user-defined verify/response timeout in am65_cpsw_iet_set_verify_timeout_count(). As per IEEE 802.3 Clause 99, the hardware performs this automatic retry up to 3 times.
Current implementation toggles LINKFAIL after the user-configured verify/response timeout in each iteration, forcing the hardware to restart verification instead of respecting the MAC_VERIFY_CNT timeout. This bypasses the hardware's automatic retry mechanism.
Fix this by moving the LINKFAIL bit toggle outside the retry loop and reducing the retry count from 20 to 3. The software now only monitors the status register while the hardware autonomously handles the 3 verification attempts at proper MAC_VERIFY_CNT intervals.
Fixes: 49a2eb9068246 ("net: ethernet: ti: am65-cpsw-qos: Add Frame Preemption MAC Merge support") Signed-off-by: Aksh Garg a-garg7@ti.com Link: https://patch.msgid.link/20251106092305.1437347-3-a-garg7@ti.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/ti/am65-cpsw-qos.c | 27 +++++++++++++------------ 1 file changed, 14 insertions(+), 13 deletions(-)
diff --git a/drivers/net/ethernet/ti/am65-cpsw-qos.c b/drivers/net/ethernet/ti/am65-cpsw-qos.c index ad06942ce461a..66e8b224827b6 100644 --- a/drivers/net/ethernet/ti/am65-cpsw-qos.c +++ b/drivers/net/ethernet/ti/am65-cpsw-qos.c @@ -317,20 +317,21 @@ static int am65_cpsw_iet_verify_wait(struct am65_cpsw_port *port) u32 ctrl, status; int try;
- try = 20; - do { - /* Reset the verify state machine by writing 1 - * to LINKFAIL - */ - ctrl = readl(port->port_base + AM65_CPSW_PN_REG_IET_CTRL); - ctrl |= AM65_CPSW_PN_IET_MAC_LINKFAIL; - writel(ctrl, port->port_base + AM65_CPSW_PN_REG_IET_CTRL); + try = 3;
- /* Clear MAC_LINKFAIL bit to start Verify. */ - ctrl = readl(port->port_base + AM65_CPSW_PN_REG_IET_CTRL); - ctrl &= ~AM65_CPSW_PN_IET_MAC_LINKFAIL; - writel(ctrl, port->port_base + AM65_CPSW_PN_REG_IET_CTRL); + /* Reset the verify state machine by writing 1 + * to LINKFAIL + */ + ctrl = readl(port->port_base + AM65_CPSW_PN_REG_IET_CTRL); + ctrl |= AM65_CPSW_PN_IET_MAC_LINKFAIL; + writel(ctrl, port->port_base + AM65_CPSW_PN_REG_IET_CTRL);
+ /* Clear MAC_LINKFAIL bit to start Verify. */ + ctrl = readl(port->port_base + AM65_CPSW_PN_REG_IET_CTRL); + ctrl &= ~AM65_CPSW_PN_IET_MAC_LINKFAIL; + writel(ctrl, port->port_base + AM65_CPSW_PN_REG_IET_CTRL); + + do { msleep(port->qos.iet.verify_time_ms);
status = readl(port->port_base + AM65_CPSW_PN_REG_IET_STATUS); @@ -352,7 +353,7 @@ static int am65_cpsw_iet_verify_wait(struct am65_cpsw_port *port) netdev_dbg(port->ndev, "MAC Merge verify error\n"); return -ENODEV; } - } while (try-- > 0); + } while (--try > 0);
netdev_dbg(port->ndev, "MAC Merge verify timeout\n"); return -ETIMEDOUT;