[PATCH net-next 0/3] Fixes and improvements to TJA1103 PHY driver

From: Vladimir Oltean <vladimir.oltean@nxp.com>

This series contains:
- an erratum workaround for the TJA1103 PHY integrated in SJA1110
- an adaptation of the driver so it prints less unnecessary information
  when probing on SJA1110
- a PTP RX timestamping bug fix

Targeting net-next since the PHY support is currently in net-next only.

Vladimir Oltean (3):
  net: phy: nxp-c45-tja11xx: demote the "no PTP support" message to
    debug
  net: phy: nxp-c45-tja11xx: fix potential RX timestamp wraparound
  net: phy: nxp-c45-tja11xx: enable MDIO write access to the
    master/slave registers

 drivers/net/phy/nxp-c45-tja11xx.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

-- 
2.25.1

From: Vladimir Oltean <vladimir.oltean@nxp.com>

The SJA1110 switch integrates TJA1103 PHYs, but in SJA1110 switch rev B
silicon, there is a bug in that the registers for selecting the 100base-T1
autoneg master/slave roles are not writable.

To enable write access to the master/slave registers, these additional
PHY writes are necessary during initialization.

The issue has been corrected in later SJA1110 silicon versions and is
not present in the standalone PHY variants, but applying the workaround
unconditionally in the driver should not do any harm.

Suggested-by: Radu Pirea (NXP OSS) <redacted>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 drivers/net/phy/nxp-c45-tja11xx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/phy/nxp-c45-tja11xx.c b/drivers/net/phy/nxp-c45-tja11xx.c
index 118b393b1cbb..b4dc112d4881 100644
--- a/drivers/net/phy/nxp-c45-tja11xx.c
+++ b/drivers/net/phy/nxp-c45-tja11xx.c

@@ -1035,6 +1035,9 @@ static int nxp_c45_config_init(struct phy_device *phydev)
 		return ret;
 	}
 
+	phy_write_mmd(phydev, MDIO_MMD_VEND1, 0x01F8, 1);
+	phy_write_mmd(phydev, MDIO_MMD_VEND1, 0x01F9, 2);
+
 	phy_set_bits_mmd(phydev, MDIO_MMD_VEND1, VEND1_PHY_CONFIG,
 			 PHY_CONFIG_AUTO);
 

-- 
2.25.1

From: Vladimir Oltean <vladimir.oltean@nxp.com>

The reconstruction procedure for partial timestamps reads the current
PTP time and fills in the low 2 bits of the second portion, as well as
the nanoseconds portion, from the actual hardware packet timestamp.
Critically, the reconstruction procedure works because it assumes that
the current PTP time is strictly larger than the hardware timestamp was:
it detects a 2-bit wraparound of the 'seconds' portion by checking whether
the 'seconds' portion of the partial hardware timestamp is larger than
the 'seconds' portion of the current time. That can only happen if the
hardware timestamp was captured by the PHY during the last phase of a
'modulo 4 seconds' interval, and the current PTP time was read by the
driver during the initial phase of the next 'modulo 4 seconds' interval.

The partial RX timestamps are added to priv->rx_queue in
nxp_c45_rxtstamp() and they are processed potentially in parallel by the
aux worker thread in nxp_c45_do_aux_work(). This means that it is
possible for nxp_c45_do_aux_work() to process more than one RX timestamp
during the same schedule.

There is one premature optimization that will cause issues: for RX
timestamping, the driver reads the current time only once, and it uses
that to reconstruct all PTP RX timestamps in the queue. For the second
and later timestamps, this will be an issue if we are processing two RX
timestamps which are to the left and to the right, respectively, of a
4-bit wraparound of the 'seconds' portion of the PTP time, and the
current PTP time is also pre-wraparound.

 0.000000000        4.000000000        8.000000000        12.000000000
 |..................|..................|..................|............>
                 ^ ^ ^ ^                                            time
                 | | | |
                 | | | process hwts 1 and hwts 2
                 | | |
                 | | hwts 2
                 | |
                 | read current PTP time
                 |
                 hwts 1

What will happen in that case is that hwts 2 (post-wraparound) will use
a stale current PTP time that is pre-wraparound.
But nxp_c45_reconstruct_ts will not detect this condition, because it is
not coded up for it, so it will reconstruct hwts 2 with a current time
from the previous 4 second interval (i.e. 0.something instead of
4.something).

This is solvable by making sure that the full 64-bit current time is
always read after the PHY has taken the partial RX timestamp. We do this
by reading the current PTP time for every timestamp in the RX queue.

Fixes: 514def5dd339 ("phy: nxp-c45-tja11xx: add timestamping support")
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 drivers/net/phy/nxp-c45-tja11xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/phy/nxp-c45-tja11xx.c b/drivers/net/phy/nxp-c45-tja11xx.c
index 902fe1aa7782..118b393b1cbb 100644
--- a/drivers/net/phy/nxp-c45-tja11xx.c
+++ b/drivers/net/phy/nxp-c45-tja11xx.c

@@ -427,8 +427,8 @@ static long nxp_c45_do_aux_work(struct ptp_clock_info *ptp)
 		nxp_c45_process_txts(priv, &hwts);
 	}
 
-	nxp_c45_ptp_gettimex64(&priv->caps, &ts, NULL);
 	while ((skb = skb_dequeue(&priv->rx_queue)) != NULL) {
+		nxp_c45_ptp_gettimex64(&priv->caps, &ts, NULL);
 		ts_raw = __be32_to_cpu(NXP_C45_SKB_CB(skb)->header->reserved2);
 		hwts.sec = ts_raw >> 30;
 		hwts.nsec = ts_raw & GENMASK(29, 0);

-- 
2.25.1

From: Vladimir Oltean <vladimir.oltean@nxp.com>

The SJA1110 switch integrates these PHYs, and they do not have support
for timestamping. This message becomes quite overwhelming:

[   10.056596] NXP C45 TJA1103 spi1.0-base-t1:01: the phy does not support PTP
[   10.112625] NXP C45 TJA1103 spi1.0-base-t1:02: the phy does not support PTP
[   10.167461] NXP C45 TJA1103 spi1.0-base-t1:03: the phy does not support PTP
[   10.223510] NXP C45 TJA1103 spi1.0-base-t1:04: the phy does not support PTP
[   10.278239] NXP C45 TJA1103 spi1.0-base-t1:05: the phy does not support PTP
[   10.332663] NXP C45 TJA1103 spi1.0-base-t1:06: the phy does not support PTP
[   15.390828] NXP C45 TJA1103 spi1.2-base-t1:01: the phy does not support PTP
[   15.445224] NXP C45 TJA1103 spi1.2-base-t1:02: the phy does not support PTP
[   15.499673] NXP C45 TJA1103 spi1.2-base-t1:03: the phy does not support PTP
[   15.554074] NXP C45 TJA1103 spi1.2-base-t1:04: the phy does not support PTP
[   15.608516] NXP C45 TJA1103 spi1.2-base-t1:05: the phy does not support PTP
[   15.662996] NXP C45 TJA1103 spi1.2-base-t1:06: the phy does not support PTP

So reduce its log level to debug.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 drivers/net/phy/nxp-c45-tja11xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/phy/nxp-c45-tja11xx.c b/drivers/net/phy/nxp-c45-tja11xx.c
index 512e4cb5d2c2..902fe1aa7782 100644
--- a/drivers/net/phy/nxp-c45-tja11xx.c
+++ b/drivers/net/phy/nxp-c45-tja11xx.c

@@ -1090,7 +1090,7 @@ static int nxp_c45_probe(struct phy_device *phydev)
 				   VEND1_PORT_ABILITIES);
 	ptp_ability = !!(ptp_ability & PTP_ABILITY);
 	if (!ptp_ability) {
-		phydev_info(phydev, "the phy does not support PTP");
+		phydev_dbg(phydev, "the phy does not support PTP");
 		goto no_ptp_support;
 	}
 

-- 
2.25.1

On Mon, Jun 14, 2021 at 03:18:47PM +0300, Vladimir Oltean wrote:

From: Vladimir Oltean <vladimir.oltean@nxp.com>

The SJA1110 switch integrates these PHYs, and they do not have support
for timestamping. This message becomes quite overwhelming:

[   10.056596] NXP C45 TJA1103 spi1.0-base-t1:01: the phy does not support PTP
[   10.112625] NXP C45 TJA1103 spi1.0-base-t1:02: the phy does not support PTP
[   10.167461] NXP C45 TJA1103 spi1.0-base-t1:03: the phy does not support PTP
[   10.223510] NXP C45 TJA1103 spi1.0-base-t1:04: the phy does not support PTP
[   10.278239] NXP C45 TJA1103 spi1.0-base-t1:05: the phy does not support PTP
[   10.332663] NXP C45 TJA1103 spi1.0-base-t1:06: the phy does not support PTP
[   15.390828] NXP C45 TJA1103 spi1.2-base-t1:01: the phy does not support PTP
[   15.445224] NXP C45 TJA1103 spi1.2-base-t1:02: the phy does not support PTP
[   15.499673] NXP C45 TJA1103 spi1.2-base-t1:03: the phy does not support PTP
[   15.554074] NXP C45 TJA1103 spi1.2-base-t1:04: the phy does not support PTP
[   15.608516] NXP C45 TJA1103 spi1.2-base-t1:05: the phy does not support PTP
[   15.662996] NXP C45 TJA1103 spi1.2-base-t1:06: the phy does not support PTP

So reduce its log level to debug.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

On Mon, Jun 14, 2021 at 03:18:49PM +0300, Vladimir Oltean wrote:

I think this deserves a comment - especially since the code uses numeric
values here.

Thanks.

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