linux-kernel - [PATCH net-next v1] net: microchip: lan743x: Reduce PTP timeout on HW failure

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Date: Thu, 2 May 2024 10:33:00 +0530
From: Rengarajan S <rengarajan.s@...rochip.com>
To: <bryan.whitehead@...rochip.com>, <UNGLinuxDriver@...rochip.com>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <richardcochran@...il.com>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: <rengarajan.s@...rochip.com>
Subject: [PATCH net-next v1] net: microchip: lan743x: Reduce PTP timeout on HW failure

The PTP_CMD_CTL is a self clearing register which controls the PTP clock
values. In the current implementation driver waits for a duration of 20
sec in case of HW failure to clear the PTP_CMD_CTL register bit. This
timeout of 20 sec is very long to recognize a HW failure, as it is
typically cleared in one clock(<16ns). Hence reducing the timeout to 1 sec
would be sufficient to conclude if there is any HW failure observed. The
usleep_range will sleep somewhere between 1 msec to 20 msec for each
iteration. By setting the PTP_CMD_CTL_TIMEOUT_CNT to 50 the max timeout
is extended to 1 sec.

Signed-off-by: Rengarajan S <rengarajan.s@...rochip.com>
---
 drivers/net/ethernet/microchip/lan743x_ptp.c | 2 +-
 drivers/net/ethernet/microchip/lan743x_ptp.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_ptp.c b/drivers/net/ethernet/microchip/lan743x_ptp.c
index 2801f08bf1c9..f8e840fd62cd 100644
--- a/drivers/net/ethernet/microchip/lan743x_ptp.c
+++ b/drivers/net/ethernet/microchip/lan743x_ptp.c
@@ -58,7 +58,7 @@ int lan743x_gpio_init(struct lan743x_adapter *adapter)
 static void lan743x_ptp_wait_till_cmd_done(struct lan743x_adapter *adapter,
 					   u32 bit_mask)
 {
-	int timeout = 1000;
+	int timeout = PTP_CMD_CTL_TIMEOUT_CNT;
 	u32 data = 0;
 
 	while (timeout &&
diff --git a/drivers/net/ethernet/microchip/lan743x_ptp.h b/drivers/net/ethernet/microchip/lan743x_ptp.h
index e26d4eff7133..0d29914cd460 100644
--- a/drivers/net/ethernet/microchip/lan743x_ptp.h
+++ b/drivers/net/ethernet/microchip/lan743x_ptp.h
@@ -21,6 +21,7 @@
 #define LAN743X_PTP_N_EXTTS		4
 #define LAN743X_PTP_N_PPS		0
 #define PCI11X1X_PTP_IO_MAX_CHANNELS	8
+#define PTP_CMD_CTL_TIMEOUT_CNT		50
 
 struct lan743x_adapter;
 
-- 
2.25.1