net: sun8i_emac: Fix DMA alignment issues with the rx / tx buffers

This fixes the following CACHE warnings when using sun8i_emac:

=> dhcp
BOOTP broadcast 1
BOOTP broadcast 2
CACHE: Misaligned operation at range [7bf594a8, 7bf59628]
BOOTP broadcast 3
CACHE: Misaligned operation at range [7bf59c90, 7bf59e10]
CACHE: Misaligned operation at range [7bf5a478, 7bf5a5f8]
DHCP client bound to address 10.42.43.80 (1009 ms)

Note this commit also changes the max rx size from 2024 to 2044,
matching what the kernel driver uses.

Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Corentin LABBE <clabbe.montjoie@gmail.com>
Cc: Amit Singh Tomar <amittomer25@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

drivers/net/sun8i_emac.c

@@ -32,7 +32,14 @@
 
 #define CONFIG_TX_DESCR_NUM	32
 #define CONFIG_RX_DESCR_NUM	32
-#define CONFIG_ETH_BUFSIZE	2024
+#define CONFIG_ETH_BUFSIZE	2048 /* Note must be dma aligned */
+
+/*
+ * The datasheet says that each descriptor can transfers up to 4096 bytes
+ * But later, the register documentation reduces that value to 2048,
+ * using 2048 cause strange behaviours and even BSP driver use 2047
+ */
+#define CONFIG_ETH_RXSIZE	2044 /* Note must fit in ETH_BUFSIZE */
 
 #define TX_TOTAL_BUFSIZE	(CONFIG_ETH_BUFSIZE * CONFIG_TX_DESCR_NUM)
 #define RX_TOTAL_BUFSIZE	(CONFIG_ETH_BUFSIZE * CONFIG_RX_DESCR_NUM)
@@ -324,7 +331,7 @@ static void rx_descs_init(struct emac_eth_dev *priv)
 		desc_p->buf_addr = (uintptr_t)&rxbuffs[idx * CONFIG_ETH_BUFSIZE]
 			;
 		desc_p->next = (uintptr_t)&desc_table_p[idx + 1];
-		desc_p->st |= CONFIG_ETH_BUFSIZE;
+		desc_p->st |= CONFIG_ETH_RXSIZE;
 		desc_p->status = BIT(31);
 	}
 
@@ -506,7 +513,7 @@ static int _sun8i_eth_recv(struct emac_eth_dev *priv, uchar **packetp)
 					roundup(data_end,
 						ARCH_DMA_MINALIGN));
 		if (good_packet) {
-			if (length > CONFIG_ETH_BUFSIZE) {
+			if (length > CONFIG_ETH_RXSIZE) {
 				printf("Received packet is too big (len=%d)\n",
 				       length);
 				return -EMSGSIZE;