sfc: Fix test for MDIO read failure

Commit 27dd2caca4eabe7c13a052b7456495ba75535e6a changed
mdio_clause45_check_mmds() to read both DEVS0 and DEVS1 registers and
to combine their values into an unsigned 32-bit mask.  This made the
following test for a negative (failure) value useless.  Fix it to
check whether either read failed.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/net/sfc/mdio_10g.c b/drivers/net/sfc/mdio_10g.c
index f9e2f95c3b48..4462fb58a3a9 100644
--- a/drivers/net/sfc/mdio_10g.c
+++ b/drivers/net/sfc/mdio_10g.c
@@ -125,24 +125,25 @@ int mdio_clause45_wait_reset_mmds(struct efx_nic *efx,
 int mdio_clause45_check_mmds(struct efx_nic *efx,
                              unsigned int mmd_mask, unsigned int fatal_mask)
 {
+        int mmd = 0, probe_mmd, devs0, devs1;
         u32 devices;
-        int mmd = 0, probe_mmd;
 
         /* Historically we have probed the PHYXS to find out what devices are
          * present,but that doesn't work so well if the PHYXS isn't expected
          * to exist, if so just find the first item in the list supplied. */
         probe_mmd = (mmd_mask & MDIO_MMDREG_DEVS_PHYXS) ? MDIO_MMD_PHYXS :
             __ffs(mmd_mask);
-        devices = (mdio_clause45_read(efx, efx->mii.phy_id,
-                                      probe_mmd, MDIO_MMDREG_DEVS0) |
-                   mdio_clause45_read(efx, efx->mii.phy_id,
-                                      probe_mmd, MDIO_MMDREG_DEVS1) << 16);
 
         /* Check all the expected MMDs are present */
-        if (devices < 0) {
+        devs0 = mdio_clause45_read(efx, efx->mii.phy_id,
+                                   probe_mmd, MDIO_MMDREG_DEVS0);
+        devs1 = mdio_clause45_read(efx, efx->mii.phy_id,
+                                   probe_mmd, MDIO_MMDREG_DEVS1);
+        if (devs0 < 0 || devs1 < 0) {
                 EFX_ERR(efx, "failed to read devices present\n");
                 return -EIO;
         }
+        devices = devs0 | (devs1 << 16);
         if ((devices & mmd_mask) != mmd_mask) {
                 EFX_ERR(efx, "required MMDs not present: got %x, "
                         "wanted %x\n", devices, mmd_mask);