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([39.170.101.209]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ab36fdc75esm19541303a91.12.2026.10.12.20.32.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Oct 2026 20:32:17 -0700 (PDT) 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, netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Zxyan Zhu Subject: [PATCH net-next v8 1/3] net: stmmac: dwmac-socfpga: complete cross-timestamp on ATSNS Date: Tue, 13 Oct 2026 11:32:05 +0800 Message-Id: <20261013033207.1684328-2-zxyan0222@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261013033207.1684328-1-zxyan0222@gmail.com> References: <20261013033207.1684328-1-zxyan0222@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 so a concurrent PTP_CLK_REQ_EXTTS request cannot flush the FIFO between the poll and the drain loop. Fixes: fd8c4f645496 ("net: stmmac: socfpga: Add hardware supported cross-timestamp") Signed-off-by: Zxyan Zhu --- .../ethernet/stmicro/stmmac/dwmac-socfpga.c | 29 ++++++++++++++----- 1 file changed, 22 insertions(+), 7 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c index 6d4bc1fe8f75..ee79b74bf21b 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c @@ -337,8 +337,18 @@ 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) { + 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 +359,14 @@ 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) { + mutex_unlock(&priv->aux_ts_lock); netdev_err(priv->dev, "%s: Wait for time sync operation timeout\n", __func__); return ret; @@ -364,8 +378,7 @@ 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++) { @@ -375,6 +388,8 @@ static int smtg_crosststamp(ktime_t *device, struct system_counterval_t *system, read_unlock_irqrestore(&priv->ptp_lock, flags); } + mutex_unlock(&priv->aux_ts_lock); + get_smtgtime(priv->mii, SMTG_MDIO_ADDR, &smtg_time); system->cycles = smtg_time; -- 2.34.1