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Subject[PATCH v2 2/2] net: phy: abort loading yt8511 driver in unsupported modes
Date
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: b1b41c047f73 ("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>
---
drivers/net/phy/motorcomm.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
index 68cd19540c67..7e6ac2c5e27e 100644
--- 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)
--
2.25.1
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