netdev - [PATCH v2 2/2] phy: nxp-c45-tja11xx: read the tx timestamp without lock

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Message-Id: <20211222213453.969005-3-radu-nicolae.pirea@oss.nxp.com>
Date:   Wed, 22 Dec 2021 23:34:53 +0200
From:   "Radu Pirea (NXP OSS)" <radu-nicolae.pirea@....nxp.com>
To:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     christian.herber@....com, andrew@...n.ch, hkallweit1@...il.com,
        linux@...linux.org.uk, davem@...emloft.net, kuba@...nel.org,
        richardcochran@...il.com,
        "Radu Pirea (NXP OSS)" <radu-nicolae.pirea@....nxp.com>
Subject: [PATCH v2 2/2] phy: nxp-c45-tja11xx: read the tx timestamp without lock

Reading the tx timestamps can be done in parallel with adjusting the LTC
value.

Calls to nxp_c45_get_hwtxts() are always serialised. If the phy
interrupt is enabled, .do_aux_work() will not call nxp_c45_get_hwtxts.

Signed-off-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@....nxp.com>
---
 drivers/net/phy/nxp-c45-tja11xx.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/phy/nxp-c45-tja11xx.c b/drivers/net/phy/nxp-c45-tja11xx.c
index 06fdbae509a79..24285a528fec9 100644
--- a/drivers/net/phy/nxp-c45-tja11xx.c
+++ b/drivers/net/phy/nxp-c45-tja11xx.c
@@ -216,7 +216,7 @@ struct nxp_c45_phy {
 	struct ptp_clock_info caps;
 	struct sk_buff_head tx_queue;
 	struct sk_buff_head rx_queue;
-	/* used to access the PTP registers atomic */
+	/* used to access the LTC registers atomically */
 	struct mutex ptp_lock;
 	int hwts_tx;
 	int hwts_rx;
@@ -386,7 +386,6 @@ static bool nxp_c45_get_hwtxts(struct nxp_c45_phy *priv,
 	bool valid;
 	u16 reg;
 
-	mutex_lock(&priv->ptp_lock);
 	phy_write_mmd(priv->phydev, MDIO_MMD_VEND1, VEND1_EGR_RING_CTRL,
 		      RING_DONE);
 	reg = phy_read_mmd(priv->phydev, MDIO_MMD_VEND1, VEND1_EGR_RING_DATA_0);
@@ -406,7 +405,6 @@ static bool nxp_c45_get_hwtxts(struct nxp_c45_phy *priv,
 	hwts->sec |= (reg & RING_DATA_3_SEC_1_0) >> 14;
 
 nxp_c45_get_hwtxts_out:
-	mutex_unlock(&priv->ptp_lock);
 	return valid;
 }
 
-- 
2.34.1