netdev - [PATCH net v2 1/2] net: mdio: mdio-bcm-unimac: Delay before first poll

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Message-Id: <20231213222744.2891184-2-justin.chen@broadcom.com>
Date: Wed, 13 Dec 2023 14:27:43 -0800
From: Justin Chen <justin.chen@...adcom.com>
To: netdev@...r.kernel.org
Cc: opendmb@...il.com,
	florian.fainelli@...adcom.com,
	bcm-kernel-feedback-list@...adcom.com,
	andrew@...n.ch,
	hkallweit1@...il.com,
	linux@...linux.org.uk,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	Justin Chen <justin.chen@...adcom.com>
Subject: [PATCH net v2 1/2] net: mdio: mdio-bcm-unimac: Delay before first poll

With a clock interval of 400 nsec and a 64 bit transactions (32 bit
preamble & 16 bit control & 16 bit data), it is reasonable to assume
the mdio transaction will take 25.6 usec. Add a 30 usec delay before
the first poll to reduce the chance of a 1000-2000 usec sleep.

Reduce the timeout from 1000ms to 100ms as it is unlikely for the bus
to take this long.

Signed-off-by: Justin Chen <justin.chen@...adcom.com>
Acked-by: Florian Fainelli <florian.fainelli@...adcom.com>
---
v2
	- Add comment to address absense of C45 support

 drivers/net/mdio/mdio-bcm-unimac.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mdio/mdio-bcm-unimac.c b/drivers/net/mdio/mdio-bcm-unimac.c
index e8cd8eef319b..297ea4a58d79 100644
--- a/drivers/net/mdio/mdio-bcm-unimac.c
+++ b/drivers/net/mdio/mdio-bcm-unimac.c
@@ -81,7 +81,13 @@ static inline unsigned int unimac_mdio_busy(struct unimac_mdio_priv *priv)
 static int unimac_mdio_poll(void *wait_func_data)
 {
 	struct unimac_mdio_priv *priv = wait_func_data;
-	unsigned int timeout = 1000;
+	unsigned int timeout = 100;
+
+	/*
+	 * C22 transactions should take ~25 usec, will need to adjust
+	 * if C45 support is added.
+	 */
+	udelay(30);
 
 	do {
 		if (!unimac_mdio_busy(priv))
-- 
2.34.1


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