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([39.170.101.209]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b09449bff2sm3920799a91.9.2026.11.04.04.50.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Nov 2026 04:50:42 -0800 (PST) From: Zxyan Zhu To: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, maxime.chevallier@bootlin.com Cc: mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com, richardcochran@gmail.com, muhammad.nazim.amirul.nazle.asmade@altera.com, rohan.g.thomas@altera.com, o.rempel@pengutronix.de, wojciech.drewek@intel.com, netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Zxyan Zhu , stable@vger.kernel.org Subject: [PATCH net-next v9 1/3] net: stmmac: dwmac-socfpga: complete cross-timestamp on ATSNS Date: Wed, 4 Nov 2026 20:50:28 +0800 Message-Id: <20261104125030.1183146-2-zxyan0222@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261104125030.1183146-1-zxyan0222@gmail.com> References: <20261104125030.1183146-1-zxyan0222@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The Agilex5 smtg_crosststamp() handler polls XGMAC_INT_STATUS for TSIS to learn that the auxiliary snapshot is latched. TSIS is a transient, read-to-clear status bit, so the poll is racy in two ways: a stale TSIS from an unrelated event satisfies it before the snapshot is latched, leaving *device unwritten while the call reports success, and a concurrent reader of XGMAC_TIMESTAMP_STATUS can clear it and make the poll time out. The FIFO level is also reported by the ATSNS count in XGMAC_TIMESTAMP_STATUS, which reading the register does not disturb. Poll ATSNS instead of TSIS, after waiting for the PTP_ACR_ATSFC FIFO clear, so a stale ATSNS cannot satisfy the poll before the new snapshot is latched. Hold aux_ts_lock across the whole sequence, and refuse the request with -EBUSY while a channel is enabled, so the PTP_ACR mask programming cannot disarm it and a concurrent request cannot flush the FIFO between the poll and the drain loop. The lock is held across the SMTG register reads as well, so a concurrent PTP_SYS_OFFSET_PRECISE cannot retrigger GPO0 while they run. The internal snapshot trigger is disarmed on the way out, including the error paths, so it does not stay armed in PTP_ACR after the cross-timestamp. Fixes: fd8c4f645496 ("net: stmmac: socfpga: Add hardware supported cross-timestamp") Cc: stable@vger.kernel.org Signed-off-by: Zxyan Zhu --- .../ethernet/stmicro/stmmac/dwmac-socfpga.c | 52 +++++++++++++++---- 1 file changed, 41 insertions(+), 11 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c index 6d4bc1fe8f75..2d3c6702e203 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c @@ -304,13 +304,15 @@ static int smtg_crosststamp(ktime_t *device, struct system_counterval_t *system, int i, ret; u32 v; + mutex_lock(&priv->aux_ts_lock); /* Both internal crosstimestamping and external triggered event - * timestamping cannot be run concurrently. + * timestamping cannot be run concurrently: the PTP_ACR mask + * programming below would disarm an external channel. */ - if (priv->plat->flags & STMMAC_FLAG_EXT_SNAPSHOT_EN) + if (priv->plat->flags & STMMAC_FLAG_EXT_SNAPSHOT_EN) { + mutex_unlock(&priv->aux_ts_lock); return -EBUSY; - - mutex_lock(&priv->aux_ts_lock); + } /* Enable Internal snapshot trigger */ acr_value = readl(ptpaddr + PTP_ACR); acr_value &= ~PTP_ACR_MASK; @@ -337,8 +339,21 @@ static int smtg_crosststamp(ktime_t *device, struct system_counterval_t *system, acr_value = readl(ptpaddr + PTP_ACR); acr_value |= PTP_ACR_ATSFC; writel(acr_value, ptpaddr + PTP_ACR); - /* Release the mutex */ - mutex_unlock(&priv->aux_ts_lock); + + /* Wait for the FIFO clear, so the poll only sees snapshots from + * this trigger. + */ + ret = readl_poll_timeout(ptpaddr + PTP_ACR, acr_value, + !(acr_value & PTP_ACR_ATSFC), 10, 10000); + if (ret) { + acr_value = readl(ptpaddr + PTP_ACR); + acr_value &= ~PTP_ACR_MASK; + writel(acr_value, ptpaddr + PTP_ACR); + mutex_unlock(&priv->aux_ts_lock); + netdev_err(priv->dev, "%s: Failed to clear snapshot FIFO\n", + __func__); + return ret; + } /* Trigger Internal snapshot signal. Create a rising edge by just toggle * the GPO0 to low and back to high. @@ -349,10 +364,17 @@ static int smtg_crosststamp(ktime_t *device, struct system_counterval_t *system, gpio_value |= XGMAC_GPIO_GPO0; writel(gpio_value, ioaddr + XGMAC_GPIO_STATUS); - /* Poll for time sync operation done */ - ret = readl_poll_timeout(priv->ioaddr + XGMAC_INT_STATUS, v, - (v & XGMAC_INT_TSIS), 100, 10000); + /* Poll ATSNS instead of the transient TSIS: the ATSNS count is + * the FIFO level and is not cleared by reading the register. + */ + ret = readl_poll_timeout(ioaddr + XGMAC_TIMESTAMP_STATUS, v, + FIELD_GET(XGMAC_TIMESTAMP_ATSNS_MASK, v), + 100, 10000); if (ret) { + acr_value = readl(ptpaddr + PTP_ACR); + acr_value &= ~PTP_ACR_MASK; + writel(acr_value, ptpaddr + PTP_ACR); + mutex_unlock(&priv->aux_ts_lock); netdev_err(priv->dev, "%s: Wait for time sync operation timeout\n", __func__); return ret; @@ -364,8 +386,7 @@ static int smtg_crosststamp(ktime_t *device, struct system_counterval_t *system, .use_nsecs = false, }; - num_snapshot = FIELD_GET(XGMAC_TIMESTAMP_ATSNS_MASK, - readl(ioaddr + XGMAC_TIMESTAMP_STATUS)); + num_snapshot = FIELD_GET(XGMAC_TIMESTAMP_ATSNS_MASK, v); /* Repeat until the timestamps are from the FIFO last segment */ for (i = 0; i < num_snapshot; i++) { @@ -375,9 +396,18 @@ static int smtg_crosststamp(ktime_t *device, struct system_counterval_t *system, read_unlock_irqrestore(&priv->ptp_lock, flags); } + /* Disarm the internal snapshot trigger, so the PTP_ACR mask does + * not stay armed behind the software state. + */ + acr_value = readl(ptpaddr + PTP_ACR); + acr_value &= ~PTP_ACR_MASK; + writel(acr_value, ptpaddr + PTP_ACR); + get_smtgtime(priv->mii, SMTG_MDIO_ADDR, &smtg_time); system->cycles = smtg_time; + mutex_unlock(&priv->aux_ts_lock); + return 0; } -- 2.34.1