drivers: net: cpsw: fix kernel warn during iperf test with interrupt pacing

When interrupt pacing is enabled, receive/transmit statistics are not
updated properly by hardware which leads to ISR return with IRQ_NONE
and inturn kernel disables the interrupt. This patch removed the checking
of receive/transmit statistics from ISR.

This patch is verified with AM335x Beagle Bone Black and below is the
kernel warn when interrupt pacing is enabled.

[  104.298254] irq 58: nobody cared (try booting with the "irqpoll" option)
[  104.305356] CPU: 0 PID: 1073 Comm: iperf Not tainted 3.12.0-rc3-00342-g77d4015 #3
[  104.313284] [<c001bb84>] (unwind_backtrace+0x0/0xf0) from [<c0017db0>] (show_stack+0x10/0x14)
[  104.322282] [<c0017db0>] (show_stack+0x10/0x14) from [<c0507920>] (dump_stack+0x78/0x94)
[  104.330816] [<c0507920>] (dump_stack+0x78/0x94) from [<c0088c1c>] (__report_bad_irq+0x20/0xc0)
[  104.339889] [<c0088c1c>] (__report_bad_irq+0x20/0xc0) from [<c008912c>] (note_interrupt+0x1dc/0x23c)
[  104.349505] [<c008912c>] (note_interrupt+0x1dc/0x23c) from [<c0086d74>] (handle_irq_event_percpu+0xc4/0x238)
[  104.359851] [<c0086d74>] (handle_irq_event_percpu+0xc4/0x238) from [<c0086f24>] (handle_irq_event+0x3c/0x5c)
[  104.370198] [<c0086f24>] (handle_irq_event+0x3c/0x5c) from [<c008991c>] (handle_level_irq+0xac/0x10c)
[  104.379907] [<c008991c>] (handle_level_irq+0xac/0x10c) from [<c00866d8>] (generic_handle_irq+0x20/0x30)
[  104.389812] [<c00866d8>] (generic_handle_irq+0x20/0x30) from [<c0014ce8>] (handle_IRQ+0x4c/0xb0)
[  104.399066] [<c0014ce8>] (handle_IRQ+0x4c/0xb0) from [<c000856c>] (omap3_intc_handle_irq+0x60/0x74)
[  104.408598] [<c000856c>] (omap3_intc_handle_irq+0x60/0x74) from [<c050d8e4>] (__irq_svc+0x44/0x5c)
[  104.418021] Exception stack(0xde4f7c00 to 0xde4f7c48)
[  104.423345] 7c00: 00000001 00000000 00000000 dd002140 60000013 de006e54 00000002 00000000
[  104.431952] 7c20: de345748 00000040 c11c8588 00018ee0 00000000 de4f7c48 c009dfc8 c050d300
[  104.440553] 7c40: 60000013 ffffffff
[  104.444237] [<c050d8e4>] (__irq_svc+0x44/0x5c) from [<c050d300>] (_raw_spin_unlock_irqrestore+0x34/0x44)
[  104.454220] [<c050d300>] (_raw_spin_unlock_irqrestore+0x34/0x44) from [<c00868c0>] (__irq_put_desc_unlock+0x14/0x38)
[  104.465295] [<c00868c0>] (__irq_put_desc_unlock+0x14/0x38) from [<c0088068>] (enable_irq+0x4c/0x74)
[  104.474829] [<c0088068>] (enable_irq+0x4c/0x74) from [<c03abd24>] (cpsw_poll+0xb8/0xdc)
[  104.483276] [<c03abd24>] (cpsw_poll+0xb8/0xdc) from [<c044ef68>] (net_rx_action+0xc0/0x1e8)
[  104.492085] [<c044ef68>] (net_rx_action+0xc0/0x1e8) from [<c0048a90>] (__do_softirq+0x100/0x27c)
[  104.501338] [<c0048a90>] (__do_softirq+0x100/0x27c) from [<c0048cd0>] (do_softirq+0x68/0x70)
[  104.510224] [<c0048cd0>] (do_softirq+0x68/0x70) from [<c0048e8c>] (local_bh_enable+0xd0/0xe4)
[  104.519211] [<c0048e8c>] (local_bh_enable+0xd0/0xe4) from [<c048c774>] (tcp_rcv_established+0x450/0x648)
[  104.529201] [<c048c774>] (tcp_rcv_established+0x450/0x648) from [<c0494904>] (tcp_v4_do_rcv+0x154/0x474)
[  104.539195] [<c0494904>] (tcp_v4_do_rcv+0x154/0x474) from [<c043d750>] (release_sock+0xac/0x1ac)
[  104.548448] [<c043d750>] (release_sock+0xac/0x1ac) from [<c04844e8>] (tcp_recvmsg+0x4d0/0xa8c)
[  104.557528] [<c04844e8>] (tcp_recvmsg+0x4d0/0xa8c) from [<c04a8720>] (inet_recvmsg+0xcc/0xf0)
[  104.566507] [<c04a8720>] (inet_recvmsg+0xcc/0xf0) from [<c0439744>] (sock_recvmsg+0x90/0xb0)
[  104.575394] [<c0439744>] (sock_recvmsg+0x90/0xb0) from [<c043b778>] (SyS_recvfrom+0x88/0xd8)
[  104.584280] [<c043b778>] (SyS_recvfrom+0x88/0xd8) from [<c043b7e0>] (sys_recv+0x18/0x20)
[  104.592805] [<c043b7e0>] (sys_recv+0x18/0x20) from [<c0013da0>] (ret_fast_syscall+0x0/0x48)
[  104.601587] handlers:
[  104.603992] [<c03acd94>] cpsw_interrupt
[  104.608040] Disabling IRQ #58

Cc: Sebastian Siewior <bigeasy@linutronix.de>
Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/cpsw.c

@@ -639,13 +639,6 @@ void cpsw_rx_handler(void *token, int len, int status)
 static irqreturn_t cpsw_interrupt(int irq, void *dev_id)
 {
 	struct cpsw_priv *priv = dev_id;
-	u32 rx, tx, rx_thresh;
-
-	rx_thresh = __raw_readl(&priv->wr_regs->rx_thresh_stat);
-	rx = __raw_readl(&priv->wr_regs->rx_stat);
-	tx = __raw_readl(&priv->wr_regs->tx_stat);
-	if (!rx_thresh && !rx && !tx)
-		return IRQ_NONE;
 
 	cpsw_intr_disable(priv);
 	if (priv->irq_enabled == true) {