netdev - [PATCH net 2/3] broadcom: fix support for PTP_EXTTS

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Message-Id: <20250918-jk-fix-bcm-phy-supported-flags-v1-2-747b60407c9c@intel.com>
Date: Thu, 18 Sep 2025 17:33:17 -0700
From: Jacob Keller <jacob.e.keller@...el.com>
To: Florian Fainelli <florian.fainelli@...adcom.com>, 
 Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, 
 Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>, 
 Russell King <linux@...linux.org.uk>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Vadim Fedorenko <vadim.fedorenko@...ux.dev>, 
 Kory Maincent <kory.maincent@...tlin.com>
Cc: Richard Cochran <richardcochran@...il.com>, 
 Yaroslav Kolomiiets <yrk@...a.com>, James Clark <jjc@...ark.com>, 
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Jacob Keller <jacob.e.keller@...el.com>, 
 Vadim Fedorenko <vadim.fedorenko@...ux.dev>
Subject: [PATCH net 2/3] broadcom: fix support for PTP_EXTTS_REQUEST2 ioctl

Commit 7c571ac57d9d ("net: ptp: introduce .supported_extts_flags to
ptp_clock_info") modified the PTP core kernel logic to validate the
supported flags for the PTP_EXTTS_REQUEST ioctls, rather than relying on
each individual driver correctly checking its flags.

The bcm_ptp_enable() function implements support for PTP_CLK_REQ_EXTTS, but
does not check the flags, and does not forward the request structure into
bcm_ptp_extts_locked().

When originally converting the bcm-phy-ptp.c code, it was unclear what
edges the hardware actually timestamped. Thus, no flags were initialized in
the .supported_extts_flags field. This results in the kernel automatically
rejecting all userspace requests for the PTP_EXTTS_REQUEST2 ioctl.

This occurs because the PTP_STRICT_FLAGS is always assumed when operating
under PTP_EXTTS_REQUEST2. This has been the case since the flags
introduction by commit 6138e687c7b6 ("ptp: Introduce strict checking of
external time stamp options.").

The bcm-phy-ptp.c logic never properly supported strict flag validation,
as it previously ignored all flags including both PTP_STRICT_FLAGS and the
PTP_FALLING_EDGE and PTP_RISING_EDGE flags.

Reports from users in the field prove that the hardware timestamps the
rising edge. Encode this in the .supported_extts_flags field. This
re-enables support for the PTP_EXTTS_REQUEST2 ioctl.

Reported-by: James Clark <jjc@...ark.com>
Fixes: 7c571ac57d9d ("net: ptp: introduce .supported_extts_flags to ptp_clock_info")
Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
---
 drivers/net/phy/bcm-phy-ptp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/phy/bcm-phy-ptp.c b/drivers/net/phy/bcm-phy-ptp.c
index 1cf695ac73cc..d3501f8487d9 100644
--- a/drivers/net/phy/bcm-phy-ptp.c
+++ b/drivers/net/phy/bcm-phy-ptp.c
@@ -738,6 +738,7 @@ static const struct ptp_clock_info bcm_ptp_clock_info = {
 	.n_per_out	= 1,
 	.n_ext_ts	= 1,
 	.supported_perout_flags = PTP_PEROUT_DUTY_CYCLE,
+	.supported_extts_flags = PTP_STRICT_FLAGS | PTP_RISING_EDGE,
 };

 static void bcm_ptp_txtstamp(struct mii_timestamper *mii_ts,

-- 
2.51.0.rc1.197.g6d975e95c9d7