linux-kernel - [PATCH net 1/4] net: lan966x: Update lan966x_ptp_get_nominal

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Date:   Sat, 9 Apr 2022 20:41:40 +0200
From:   Horatiu Vultur <horatiu.vultur@...rochip.com>
To:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <UNGLinuxDriver@...rochip.com>, <davem@...emloft.net>,
        <kuba@...nel.org>, <pabeni@...hat.com>,
        Horatiu Vultur <horatiu.vultur@...rochip.com>
Subject: [PATCH net 1/4] net: lan966x: Update lan966x_ptp_get_nominal_value

The clk_per_cfg register represents the value added to the system clock
for each clock cycle. The issue is that the default value is wrong,
meaning that in case the DUT was a grandmaster then everone in the
network was too slow. In case there was a grandmaster, then there is no
issue because the DUT will configure clk_per_cfg register based on the
master frequency.

Fixes: d096459494a887 ("net: lan966x: Add support for ptp clocks")
Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
---
 drivers/net/ethernet/microchip/lan966x/lan966x_ptp.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_ptp.c b/drivers/net/ethernet/microchip/lan966x/lan966x_ptp.c
index ae782778d6dd..0a1041da4384 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_ptp.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_ptp.c
@@ -29,10 +29,10 @@ enum {
 
 static u64 lan966x_ptp_get_nominal_value(void)
 {
-	u64 res = 0x304d2df1;
-
-	res <<= 32;
-	return res;
+	/* This is the default value that for each system clock, the time of day
+	 * is increased. It has the format 5.59 nanosecond.
+	 */
+	return 0x304d4873ecade305;
 }
 
 int lan966x_ptp_hwtstamp_set(struct lan966x_port *port, struct ifreq *ifr)
-- 
2.33.0