mpc85xx: Fix NAPI poll mechanism in GIANFAR ethernet driver

This patch fixes the NAPI poll mechanism in the GIANFAR ethernet driver, which
was not properly working since Linus Kernel Version 3,8.
Therefore the workaround patch to downgrade the GIANFAR ethernet driver to
Kernelversion v3.8 is obsoete.
This patch was extensivly testes with different network loads and types of
traffic. There is quite a substantial user base that reports proper Ethernet
function with TPlink-4900. This patch is based on the fixes from GINAFAR
maintainer Claudiu Manoli.

Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@38865 3c298f89-4303-0410-b956-a3cf2f4a3e73

1 files changed, 109 insertions, 0 deletions

diff --git a/target/linux/mpc85xx/patches-3.10/200-fix_gianfar_napi_poll.patch b/target/linux/mpc85xx/patches-3.10/200-fix_gianfar_napi_poll.patch
new file mode 100644
index 0000000000..a1877be921
--- /dev/null
+++ b/target/linux/mpc85xx/patches-3.10/200-fix_gianfar_napi_poll.patch
@@ -0,0 +1,109 @@
+--- a/drivers/net/ethernet/freescale/gianfar.c
++++ b/drivers/net/ethernet/freescale/gianfar.c
+@@ -2835,7 +2835,7 @@ static int gfar_poll(struct napi_struct 
+ 	struct gfar_priv_rx_q *rx_queue = NULL;
+ 	int work_done = 0, work_done_per_q = 0;
+ 	int i, budget_per_q = 0;
+-	int has_tx_work;
++	int has_tx_work = 0;
+ 	unsigned long rstat_rxf;
+ 	int num_act_queues;
+ 
+@@ -2850,62 +2850,48 @@ static int gfar_poll(struct napi_struct 
+ 	if (num_act_queues)
+ 		budget_per_q = budget/num_act_queues;
+ 
+-	while (1) {
+-		has_tx_work = 0;
+-		for_each_set_bit(i, &gfargrp->tx_bit_map, priv->num_tx_queues) {
+-			tx_queue = priv->tx_queue[i];
+-			/* run Tx cleanup to completion */
+-			if (tx_queue->tx_skbuff[tx_queue->skb_dirtytx]) {
+-				gfar_clean_tx_ring(tx_queue);
+-				has_tx_work = 1;
+-			}
+-		}
+-
+-		for_each_set_bit(i, &gfargrp->rx_bit_map, priv->num_rx_queues) {
+-			/* skip queue if not active */
+-			if (!(rstat_rxf & (RSTAT_CLEAR_RXF0 >> i)))
+-				continue;
+-
+-			rx_queue = priv->rx_queue[i];
+-			work_done_per_q =
+-				gfar_clean_rx_ring(rx_queue, budget_per_q);
+-			work_done += work_done_per_q;
+-
+-			/* finished processing this queue */
+-			if (work_done_per_q < budget_per_q) {
+-				/* clear active queue hw indication */
+-				gfar_write(&regs->rstat,
+-					   RSTAT_CLEAR_RXF0 >> i);
+-				rstat_rxf &= ~(RSTAT_CLEAR_RXF0 >> i);
+-				num_act_queues--;
+-
+-				if (!num_act_queues)
+-					break;
+-				/* recompute budget per Rx queue */
+-				budget_per_q =
+-					(budget - work_done) / num_act_queues;
+-			}
++	for_each_set_bit(i, &gfargrp->tx_bit_map, priv->num_tx_queues) {
++		tx_queue = priv->tx_queue[i];
++		/* run Tx cleanup to completion */
++		if (tx_queue->tx_skbuff[tx_queue->skb_dirtytx]) {
++			gfar_clean_tx_ring(tx_queue);
++			has_tx_work = 1;
+ 		}
++	}
+ 
+-		if (work_done >= budget)
+-			break;
++	for_each_set_bit(i, &gfargrp->rx_bit_map, priv->num_rx_queues) {
++		/* skip queue if not active */
++		if (!(rstat_rxf & (RSTAT_CLEAR_RXF0 >> i)))
++			continue;
++
++		rx_queue = priv->rx_queue[i];
++		work_done_per_q = gfar_clean_rx_ring(rx_queue, budget_per_q);
++		work_done += work_done_per_q;
++
++		/* finished processing this queue */
++		if (work_done_per_q < budget_per_q) {
++			/* clear active queue hw indication */
++			gfar_write(&regs->rstat, RSTAT_CLEAR_RXF0 >> i);
++			num_act_queues--;
+ 
+-		if (!num_act_queues && !has_tx_work) {
++			if (!num_act_queues)
++				break;
++		}
++	}
+ 
+-			napi_complete(napi);
++	if (!num_act_queues && !has_tx_work) {
++		napi_complete(napi);
+ 
+-			/* Clear the halt bit in RSTAT */
+-			gfar_write(&regs->rstat, gfargrp->rstat);
++		/* Clear the halt bit in RSTAT */
++		gfar_write(&regs->rstat, gfargrp->rstat);
+ 
+-			gfar_write(&regs->imask, IMASK_DEFAULT);
++		gfar_write(&regs->imask, IMASK_DEFAULT);
+ 
+-			/* If we are coalescing interrupts, update the timer
+-			 * Otherwise, clear it
+-			 */
+-			gfar_configure_coalescing(priv, gfargrp->rx_bit_map,
+-						  gfargrp->tx_bit_map);
+-			break;
+-		}
++		/* If we are coalescing interrupts, update the timer
++		 * Otherwise, clear it
++		 */
++		gfar_configure_coalescing(priv, gfargrp->rx_bit_map,
++					  gfargrp->tx_bit_map);
+ 	}
+ 
+ 	return work_done;