On Wed, Jun 17, 2020 at 06:19:25PM +0200, Andrew Lunn wrote:
> On Wed, Jun 17, 2020 at 11:33:40PM +0800, Dejin Zheng wrote:
> > Commit 7ae7ad2f11ef47 ("net: phy: smsc: use phy_read_poll_timeout()
> > to simplify the code") will print a lot of logs as follows when Ethernet
> > cable is not connected:
> >
> > [ 4.473105] SMSC LAN8710/LAN8720 2188000.ethernet-1:00:
> > lan87xx_read_status failed: -110
> >
> > So fix it by read_poll_timeout().
>
> Do you have a more detailed explanation of what is going on here?
>
> After a lot of thought, i think i can see how this happens. But the
> commit message should really spell out why this is the correct fix.
>
Hi Andrew:
Kevin report a bug for me in link[1], I check the Commit 7ae7ad2f11ef47
("net: phy: smsc: use phy_read_poll_timeout() to simplify the code") and
found it change the original behavior in smsc driver. It does not has
any error message whether it is timeout or phy_read fails, but this Commit
will changed it and will print some error messages by
phy_read_poll_timeout() when it is timeout or phy_read fails. so use the
read_poll_timeout() to replace phy_read_poll_timeout() to fix this
issue. the read_poll_timeout() does not print any log when it goes
wrong.
the original codes is that:
/* Wait max 640 ms to detect energy */
for (i = 0; i < 64; i++) {
/* Sleep to allow link test pulses to be sent */
msleep(10);
rc = phy_read(phydev, MII_LAN83C185_CTRL_STATUS);
if (rc < 0)
return rc;
if (rc & MII_LAN83C185_ENERGYON)
break;
}
Commit 7ae7ad2f11ef47 modify it as this:
phy_read_poll_timeout(phydev, MII_LAN83C185_CTRL_STATUS,
rc & MII_LAN83C185_ENERGYON, 10000,
640000, true);
if (rc < 0)
return rc;
the phy_read_poll_timeout() will print a error log by phydev_err()
when timeout or rc < 0. read_poll_timeout() just return timeout
error and does not print any error log.
#define phy_read_poll_timeout(phydev, regnum, val, cond, sleep_us, \
timeout_us, sleep_before_read) \
({ \
int __ret = read_poll_timeout(phy_read, val, (cond) || val < 0, \
sleep_us, timeout_us, sleep_before_read, phydev, regnum); \
if (val < 0) \
__ret = val; \
if (__ret) \
phydev_err(phydev, "%s failed: %d\n", __func__, __ret); \
__ret; \
})
So use read_poll_timeout Use read_poll_timeout() to be consistent with the
original code.
link[1]: https://lkml.org/lkml/2020/6/1/1408
> Thanks
> Andrew
