drivers: net: xgene: fix: Use separate resources

This patch fixes the following kernel crash during SGMII based 1GbE probe.

	BUG: Bad page state in process swapper/0  pfn:40fe6ad
	page:ffffffbee37a75d8 count:-1 mapcount:0 mapping:          (null) index:0x0
	flags: 0x0()
	page dumped because: nonzero _count
	Modules linked in:
	CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.17.0+ #7
	Call trace:
	[<ffffffc000087fa0>] dump_backtrace+0x0/0x12c
	[<ffffffc0000880dc>] show_stack+0x10/0x1c
	[<ffffffc0004d981c>] dump_stack+0x74/0xc4
	[<ffffffc00012fe70>] bad_page+0xd8/0x128
	[<ffffffc000133000>] get_page_from_freelist+0x4b8/0x640
	[<ffffffc000133260>] __alloc_pages_nodemask+0xd8/0x834
	[<ffffffc0004194f8>] __netdev_alloc_frag+0x124/0x1b8
	[<ffffffc00041bfdc>] __netdev_alloc_skb+0x90/0x10c
	[<ffffffc00039ff30>] xgene_enet_refill_bufpool+0x11c/0x280
	[<ffffffc0003a11a4>] xgene_enet_process_ring+0x168/0x340
	[<ffffffc0003a1498>] xgene_enet_napi+0x1c/0x50
	[<ffffffc00042b454>] net_rx_action+0xc8/0x18c
	[<ffffffc0000b0880>] __do_softirq+0x114/0x24c
	[<ffffffc0000b0c34>] irq_exit+0x94/0xc8
	[<ffffffc0000e68a0>] __handle_domain_irq+0x8c/0xf4
	[<ffffffc000081288>] gic_handle_irq+0x30/0x7c

This was due to hardware resource sharing conflict with the firmware. This
patch fixes this crash by using resources (descriptor ring, prefetch buffer)
that are not shared.
Signed-off-by: Iyappan Subramanian <isubramanian@apm.com>
Signed-off-by: Keyur Chudgar <kchudgar@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/apm/xgene/xgene_enet_main.c

@@ -639,9 +639,9 @@ static int xgene_enet_create_desc_rings(struct net_device *ndev)
 	struct device *dev = ndev_to_dev(ndev);
 	struct xgene_enet_desc_ring *rx_ring, *tx_ring, *cp_ring;
 	struct xgene_enet_desc_ring *buf_pool = NULL;
-	u8 cpu_bufnum = 0, eth_bufnum = 0;
-	u8 bp_bufnum = 0x20;
-	u16 ring_id, ring_num = 0;
+	u8 cpu_bufnum = 0, eth_bufnum = START_ETH_BUFNUM;
+	u8 bp_bufnum = START_BP_BUFNUM;
+	u16 ring_id, ring_num = START_RING_NUM;
 	int ret;
 
 	/* allocate rx descriptor ring */

drivers/net/ethernet/apm/xgene/xgene_enet_main.h

@@ -38,6 +38,9 @@
 #define SKB_BUFFER_SIZE		(XGENE_ENET_MAX_MTU - NET_IP_ALIGN)
 #define NUM_PKT_BUF	64
 #define NUM_BUFPOOL	32
+#define START_ETH_BUFNUM	2
+#define START_BP_BUFNUM		0x22
+#define START_RING_NUM		8
 
 #define PHY_POLL_LINK_ON	(10 * HZ)
 #define PHY_POLL_LINK_OFF	(PHY_POLL_LINK_ON / 5)