[PATCH 3/7] net: fec_imx: Read data_length only once

Andrey Smirnov andrew.smirnov at gmail.com
Mon Sep 17 22:21:18 PDT 2018


Data length of a given Rx data descriptor isn't going to change until
that descriptor is processed and given back to HW. Re-work the code to
save and re-use that value instead.

Signed-off-by: Andrey Smirnov <andrew.smirnov at gmail.com>
---
 drivers/net/fec_imx.c | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/drivers/net/fec_imx.c b/drivers/net/fec_imx.c
index 25e2425d6..36218f3c9 100644
--- a/drivers/net/fec_imx.c
+++ b/drivers/net/fec_imx.c
@@ -574,20 +574,23 @@ static int fec_recv(struct eth_device *dev)
 	if (bd_status & FEC_RBD_ERR) {
 		dev_warn(&dev->dev, "error frame: 0x%p 0x%08x\n",
 			 rbd, bd_status);
-	} else if ((bd_status & FEC_RBD_LAST) &&
-		   ((readw(&rbd->data_length) - 4) > 14)) {
-		if (fec_is_imx28(fec))
-			imx28_fix_endianess_rd(
-				phys_to_virt(readl(&rbd->data_pointer)),
-				(readw(&rbd->data_length) + 3) >> 2);
-
-		/*
-		 * Get buffer address and size
-		 */
-		frame = phys_to_virt(readl(&rbd->data_pointer));
-		frame_length = readw(&rbd->data_length) - 4;
-		net_receive(dev, frame->data, frame_length);
-		len = frame_length;
+	} else if (bd_status & FEC_RBD_LAST) {
+		const uint16_t data_length = readw(&rbd->data_length);
+
+		if (data_length - 4 > 14) {
+			if (fec_is_imx28(fec))
+				imx28_fix_endianess_rd(
+					phys_to_virt(readl(&rbd->data_pointer)),
+					(data_length + 3) >> 2);
+
+			/*
+			 * Get buffer address and size
+			 */
+			frame = phys_to_virt(readl(&rbd->data_pointer));
+			frame_length = data_length - 4;
+			net_receive(dev, frame->data, frame_length);
+			len = frame_length;
+		}
 	}
 	/*
 	 * free the current buffer, restart the engine
-- 
2.17.1




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