net: phy: abort loading yt8511 driver in unsupported modes

While investigating the clang `ge` uninitialized variable report, it was
discovered the default switch would have unintended consequences. Due to
the switch to __phy_modify, the driver would modify the ID values in the
default scenario.

Fix this by promoting the interface mode switch and aborting when the
mode is not a supported RGMII mode.

This prevents the `ge` and `fe` variables from ever being used
uninitialized.

Fixes: 48e8c6f1612b ("net: phy: add driver for Motorcomm yt8511 phy")
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Peter Geis <pgwipeout@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
index 68cd195..7e6ac2c 100644 (file)
--- a/drivers/net/phy/motorcomm.c
+++ b/drivers/net/phy/motorcomm.c
@@ -53,15 +53,10 @@ static int yt8511_config_init(struct phy_device *phydev)
        int oldpage, ret = 0;
        unsigned int ge, fe;
 
-       /* set clock mode to 125mhz */
        oldpage = phy_select_page(phydev, YT8511_EXT_CLK_GATE);
        if (oldpage < 0)
                goto err_restore_page;
 
-       ret = __phy_modify(phydev, YT8511_PAGE, 0, YT8511_CLK_125M);
-       if (ret < 0)
-               goto err_restore_page;
-
        /* set rgmii delay mode */
        switch (phydev->interface) {
        case PHY_INTERFACE_MODE_RGMII:
@@ -80,14 +75,20 @@ static int yt8511_config_init(struct phy_device *phydev)
                ge = YT8511_DELAY_RX | YT8511_DELAY_GE_TX_EN;
                fe = YT8511_DELAY_FE_TX_EN;
                break;
-       default: /* leave everything alone in other modes */
-               break;
+       default: /* do not support other modes */
+               ret = -EOPNOTSUPP;
+               goto err_restore_page;
        }
 
        ret = __phy_modify(phydev, YT8511_PAGE, (YT8511_DELAY_RX | YT8511_DELAY_GE_TX_EN), ge);
        if (ret < 0)
                goto err_restore_page;
 
+       /* set clock mode to 125mhz */
+       ret = __phy_modify(phydev, YT8511_PAGE, 0, YT8511_CLK_125M);
+       if (ret < 0)
+               goto err_restore_page;
+
        /* fast ethernet delay is in a separate page */
        ret = __phy_write(phydev, YT8511_PAGE_SELECT, YT8511_EXT_DELAY_DRIVE);
        if (ret < 0)