octeontx2: fix -Wnonnull warning

When compile testing this driver on a platform on which probe() is
known to fail at compile time, gcc warns about the cgx_lmactype_string[]
array being uninitialized:

In function 'strncpy',
    inlined from 'link_status_user_format' at /git/arm-soc/drivers/net/ethernet/marvell/octeontx2/af/cgx.c:838:2,
    inlined from 'cgx_link_change_handler' at /git/arm-soc/drivers/net/ethernet/marvell/octeontx2/af/cgx.c:853:2:
include/linux/fortify-string.h:27:30: error: argument 2 null where non-null expected [-Werror=nonnull]
   27 | #define __underlying_strncpy __builtin_strncpy

Address this by turning the runtime initialization into a fixed array,
which should also produce better code.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/octeontx2/af/cgx.c

@@ -30,10 +30,35 @@
 static LIST_HEAD(cgx_list);
 
 /* Convert firmware speed encoding to user format(Mbps) */
-static u32 cgx_speed_mbps[CGX_LINK_SPEED_MAX];
+static const u32 cgx_speed_mbps[CGX_LINK_SPEED_MAX] = {
+	[CGX_LINK_NONE] = 0,
+	[CGX_LINK_10M] = 10,
+	[CGX_LINK_100M] = 100,
+	[CGX_LINK_1G] = 1000,
+	[CGX_LINK_2HG] = 2500,
+	[CGX_LINK_5G] = 5000,
+	[CGX_LINK_10G] = 10000,
+	[CGX_LINK_20G] = 20000,
+	[CGX_LINK_25G] = 25000,
+	[CGX_LINK_40G] = 40000,
+	[CGX_LINK_50G] = 50000,
+	[CGX_LINK_80G] = 80000,
+	[CGX_LINK_100G] = 100000,
+};
 
 /* Convert firmware lmac type encoding to string */
-static char *cgx_lmactype_string[LMAC_MODE_MAX];
+static const char *cgx_lmactype_string[LMAC_MODE_MAX] = {
+	[LMAC_MODE_SGMII] = "SGMII",
+	[LMAC_MODE_XAUI] = "XAUI",
+	[LMAC_MODE_RXAUI] = "RXAUI",
+	[LMAC_MODE_10G_R] = "10G_R",
+	[LMAC_MODE_40G_R] = "40G_R",
+	[LMAC_MODE_QSGMII] = "QSGMII",
+	[LMAC_MODE_25G_R] = "25G_R",
+	[LMAC_MODE_50G_R] = "50G_R",
+	[LMAC_MODE_100G_R] = "100G_R",
+	[LMAC_MODE_USXGMII] = "USXGMII",
+};
 
 /* CGX PHY management internal APIs */
 static int cgx_fwi_link_change(struct cgx *cgx, int lmac_id, bool en);
@@ -659,34 +684,6 @@ int cgx_fwi_cmd_generic(u64 req, u64 *resp, struct cgx *cgx, int lmac_id)
 	return err;
 }
 
-static inline void cgx_link_usertable_init(void)
-{
-	cgx_speed_mbps[CGX_LINK_NONE] = 0;
-	cgx_speed_mbps[CGX_LINK_10M] = 10;
-	cgx_speed_mbps[CGX_LINK_100M] = 100;
-	cgx_speed_mbps[CGX_LINK_1G] = 1000;
-	cgx_speed_mbps[CGX_LINK_2HG] = 2500;
-	cgx_speed_mbps[CGX_LINK_5G] = 5000;
-	cgx_speed_mbps[CGX_LINK_10G] = 10000;
-	cgx_speed_mbps[CGX_LINK_20G] = 20000;
-	cgx_speed_mbps[CGX_LINK_25G] = 25000;
-	cgx_speed_mbps[CGX_LINK_40G] = 40000;
-	cgx_speed_mbps[CGX_LINK_50G] = 50000;
-	cgx_speed_mbps[CGX_LINK_80G] = 80000;
-	cgx_speed_mbps[CGX_LINK_100G] = 100000;
-
-	cgx_lmactype_string[LMAC_MODE_SGMII] = "SGMII";
-	cgx_lmactype_string[LMAC_MODE_XAUI] = "XAUI";
-	cgx_lmactype_string[LMAC_MODE_RXAUI] = "RXAUI";
-	cgx_lmactype_string[LMAC_MODE_10G_R] = "10G_R";
-	cgx_lmactype_string[LMAC_MODE_40G_R] = "40G_R";
-	cgx_lmactype_string[LMAC_MODE_QSGMII] = "QSGMII";
-	cgx_lmactype_string[LMAC_MODE_25G_R] = "25G_R";
-	cgx_lmactype_string[LMAC_MODE_50G_R] = "50G_R";
-	cgx_lmactype_string[LMAC_MODE_100G_R] = "100G_R";
-	cgx_lmactype_string[LMAC_MODE_USXGMII] = "USXGMII";
-}
-
 static int cgx_link_usertable_index_map(int speed)
 {
 	switch (speed) {
@@ -828,7 +825,7 @@ static inline void link_status_user_format(u64 lstat,
 					   struct cgx_link_user_info *linfo,
 					   struct cgx *cgx, u8 lmac_id)
 {
-	char *lmac_string;
+	const char *lmac_string;
 
 	linfo->link_up = FIELD_GET(RESP_LINKSTAT_UP, lstat);
 	linfo->full_duplex = FIELD_GET(RESP_LINKSTAT_FDUPLEX, lstat);
@@ -1377,7 +1374,6 @@ static int cgx_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	list_add(&cgx->cgx_list, &cgx_list);
 
-	cgx_link_usertable_init();
 
 	cgx_populate_features(cgx);