[PATCH net-next 1/5] net: gemini: Look up L3 maxlen from table

[Linus Walleij]

The code to calculate the hardware register enumerator
for the maximum L3 length isn't entirely simple to read.
Use the existing defines and rewrite the function into a
table look-up.

Signed-off-by: Linus Walleij <linus.wall...@linaro.org>
---
 drivers/net/ethernet/cortina/gemini.c | 61 ++++++++++++++++++++-------
 1 file changed, 46 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/cortina/gemini.c 
b/drivers/net/ethernet/cortina/gemini.c
index 6d7404f66f84..8fc31723f700 100644
--- a/drivers/net/ethernet/cortina/gemini.c
+++ b/drivers/net/ethernet/cortina/gemini.c
@@ -401,26 +401,57 @@ static int gmac_setup_phy(struct net_device *netdev)
        return 0;
 }
 
-static int gmac_pick_rx_max_len(int max_l3_len)
-{
-       /* index = CONFIG_MAXLEN_XXX values */
-       static const int max_len[8] = {
-               1536, 1518, 1522, 1542,
-               9212, 10236, 1518, 1518
-       };
-       int i, n = 5;
+/* The maximum frame length is not logically enumerated in the
+ * hardware, so we do a table lookup to find the applicable max
+ * frame length.
+ */
+struct gmac_max_framelen {
+       unsigned int max_l3_len;
+       u8 val;
+};
 
-       max_l3_len += ETH_HLEN + VLAN_HLEN;
+static const struct gmac_max_framelen gmac_maxlens[] = {
+       {
+               .max_l3_len = 1518,
+               .val = CONFIG0_MAXLEN_1518,
+       },
+       {
+               .max_l3_len = 1522,
+               .val = CONFIG0_MAXLEN_1522,
+       },
+       {
+               .max_l3_len = 1536,
+               .val = CONFIG0_MAXLEN_1536,
+       },
+       {
+               .max_l3_len = 1542,
+               .val = CONFIG0_MAXLEN_1542,
+       },
+       {
+               .max_l3_len = 9212,
+               .val = CONFIG0_MAXLEN_9k,
+       },
+       {
+               .max_l3_len = 10236,
+               .val = CONFIG0_MAXLEN_10k,
+       },
+};
+
+static int gmac_pick_rx_max_len(unsigned int max_l3_len)
+{
+       const struct gmac_max_framelen *maxlen;
+       int maxtot;
+       int i;
 
-       if (max_l3_len > max_len[n])
-               return -1;
+       maxtot = max_l3_len + ETH_HLEN + VLAN_HLEN;
 
-       for (i = 0; i < 5; i++) {
-               if (max_len[i] >= max_l3_len && max_len[i] < max_len[n])
-                       n = i;
+       for (i = 0; i < ARRAY_SIZE(gmac_maxlens); i++) {
+               maxlen = &gmac_maxlens[i];
+               if (maxtot <= maxlen->max_l3_len)
+                       return maxlen->val;
        }
 
-       return n;
+       return -1;
 }
 
 static int gmac_init(struct net_device *netdev)
-- 
2.17.1