Commit eb7e33d0 authored by Pawel Dembicki's avatar Pawel Dembicki Committed by Jakub Kicinski
Browse files

net: dsa: vsc73xx: use read_poll_timeout instead delay loop 



Switch the delay loop during the Arbiter empty check from
vsc73xx_adjust_link() to use read_poll_timeout(). Functionally,
one msleep() call is eliminated at the end of the loop in the timeout
case.

As Russell King suggested:

"This [change] avoids the issue that on the last iteration, the code reads
the register, tests it, finds the condition that's being waiting for is
false, _then_ waits and end up printing the error message - that last
wait is rather useless, and as the arbiter state isn't checked after
waiting, it could be that we had success during the last wait."

Suggested-by: default avatarRussell King <linux@armlinux.org.uk>
Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Reviewed-by: default avatarFlorian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: default avatarPawel Dembicki <paweldembicki@gmail.com>
Link: https://lore.kernel.org/r/20240417205048.3542839-2-paweldembicki@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent c51db4ac

drivers/net/dsa/vitesse-vsc73xx-core.c

+16 −14
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/device.h>

#include <linux/iopoll.h>

#include <linux/of.h>

#include <linux/of_mdio.h>

#include <linux/bitops.h>
@@ -268,6 +269,9 @@ 
#define IS_7398(a) ((a)->chipid == VSC73XX_CHIPID_ID_7398)

#define IS_739X(a) (IS_7395(a) || IS_7398(a))



#define VSC73XX_POLL_SLEEP_US		1000

#define VSC73XX_POLL_TIMEOUT_US		10000



struct vsc73xx_counter {

	u8 counter;

	const char *name;
@@ -779,7 +783,7 @@ static void vsc73xx_adjust_link(struct dsa_switch *ds, int port, 
	 * after a PHY or the CPU port comes up or down.

	 */

	if (!phydev->link) {

		int maxloop = 10;

		int ret, err;



		dev_dbg(vsc->dev, "port %d: went down\n",

			port);
@@ -794,19 +798,17 @@ static void vsc73xx_adjust_link(struct dsa_switch *ds, int port, 
				    VSC73XX_ARBDISC, BIT(port), BIT(port));



		/* Wait until queue is empty */

		vsc73xx_read(vsc, VSC73XX_BLOCK_ARBITER, 0,

			     VSC73XX_ARBEMPTY, &val);

		while (!(val & BIT(port))) {

			msleep(1);

			vsc73xx_read(vsc, VSC73XX_BLOCK_ARBITER, 0,

		ret = read_poll_timeout(vsc73xx_read, err,

					err < 0 || (val & BIT(port)),

					VSC73XX_POLL_SLEEP_US,

					VSC73XX_POLL_TIMEOUT_US, false,

					vsc, VSC73XX_BLOCK_ARBITER, 0,

					VSC73XX_ARBEMPTY, &val);

			if (--maxloop == 0) {

		if (ret)

			dev_err(vsc->dev,

				"timeout waiting for block arbiter\n");

				/* Continue anyway */

				break;

			}

		}

		else if (err < 0)

			dev_err(vsc->dev, "error reading arbiter\n");



		/* Put this port into reset */

		vsc73xx_write(vsc, VSC73XX_BLOCK_MAC, port, VSC73XX_MAC_CFG,