[PATCH] phy: Fix phy_string_for_interface() function

["Pali Rohár" <pali@kernel.org>]

Commit c677fb1e3196 ("phy: Move PHY_INTERFACE_MODE_NA to the beginning of
the enum definition") broke function phy_string_for_interface(). And
therefore completely broke support for 2500base-x mode in Armada 3720
comphy driver.

Since that commit function phy_string_for_interface() returns constant
value PHY_INTERFACE_MODE_NA because PHY_INTERFACE_MODE_NA from moved from
end to the beginning.

Previous value of PHY_INTERFACE_MODE_NA was PHY_INTERFACE_MODE_MAX-1. So
change phy_string_for_interface() code to check upper bound via previous
value.

This patch fixes 2500base-x mode on Armada 3720

Fixes: c677fb1e3196 ("phy: Move PHY_INTERFACE_MODE_NA to the beginning of the enum definition")
Signed-off-by: Pali Rohár <pali@kernel.org>
---
 include/phy_interface.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/phy_interface.h b/include/phy_interface.h
index ce3b5004ec22..fed3357b9a26 100644
--- a/include/phy_interface.h
+++ b/include/phy_interface.h
@@ -85,7 +85,7 @@ static const char * const backplane_mode_strings[] = {
 static inline const char *phy_string_for_interface(phy_interface_t i)
 {
 	/* Default to unknown */
-	if (i > PHY_INTERFACE_MODE_NA)
+	if (i >= PHY_INTERFACE_MODE_MAX)
 		i = PHY_INTERFACE_MODE_NA;
 
 	return phy_interface_strings[i];
-- 
2.20.1