net: ethernet: ti: cpsw: optimize end of poll cycle

Check budget fullness only after it's updated and update
channel mask only once to keep budget balance between channels.
It's also needed for farther changes.
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/cpsw.c

@@ -788,19 +788,13 @@ static int cpsw_tx_poll(struct napi_struct *napi_tx, int budget)
 
 	/* process every unprocessed channel */
 	ch_map = cpdma_ctrl_txchs_state(cpsw->dma);
-	for (ch = 0, num_tx = 0; num_tx < budget; ch_map >>= 1, ch++) {
-		if (!ch_map) {
-			ch_map = cpdma_ctrl_txchs_state(cpsw->dma);
-			if (!ch_map)
-				break;
-
-			ch = 0;
-		}
-
+	for (ch = 0, num_tx = 0; ch_map; ch_map >>= 1, ch++) {
 		if (!(ch_map & 0x01))
 			continue;
 
 		num_tx += cpdma_chan_process(cpsw->txch[ch], budget - num_tx);
+		if (num_tx >= budget)
+			break;
 	}
 
 	if (num_tx < budget) {
@@ -823,19 +817,13 @@ static int cpsw_rx_poll(struct napi_struct *napi_rx, int budget)
 
 	/* process every unprocessed channel */
 	ch_map = cpdma_ctrl_rxchs_state(cpsw->dma);
-	for (ch = 0, num_rx = 0; num_rx < budget; ch_map >>= 1, ch++) {
-		if (!ch_map) {
-			ch_map = cpdma_ctrl_rxchs_state(cpsw->dma);
-			if (!ch_map)
-				break;
-
-			ch = 0;
-		}
-
+	for (ch = 0, num_rx = 0; ch_map; ch_map >>= 1, ch++) {
 		if (!(ch_map & 0x01))
 			continue;
 
 		num_rx += cpdma_chan_process(cpsw->rxch[ch], budget - num_rx);
+		if (num_rx >= budget)
+			break;
 	}
 
 	if (num_rx < budget) {