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Date: Thu, 18 Jun 2020 01:50:39 +0800 From: Dejin Zheng <zhengdejin5@...il.com> To: Andrew Lunn <andrew@...n.ch> Cc: f.fainelli@...il.com, hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, Kevin Groeneveld <kgroeneveld@...il.com> Subject: Re: [PATCH net v1] net: phy: smsc: fix printing too many logs 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
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