linux-kernel - [PATCH net-next 06/15] net: macb: simplify macb_dma_desc_get

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Message-Id: <20251014-macb-cleanup-v1-6-31cd266e22cd@bootlin.com>
Date: Tue, 14 Oct 2025 17:25:07 +0200
From: Théo Lebrun <theo.lebrun@...tlin.com>
To: Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Nicolas Ferre <nicolas.ferre@...rochip.com>, 
 Claudiu Beznea <claudiu.beznea@...on.dev>, 
 Richard Cochran <richardcochran@...il.com>, 
 Russell King <linux@...linux.org.uk>
Cc: netdev@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>, 
 Tawfik Bayouk <tawfik.bayouk@...ileye.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Grégory Clement <gregory.clement@...tlin.com>, 
 Benoît Monin <benoit.monin@...tlin.com>, 
 Maxime Chevallier <maxime.chevallier@...tlin.com>, 
 Théo Lebrun <theo.lebrun@...tlin.com>
Subject: [PATCH net-next 06/15] net: macb: simplify
 macb_dma_desc_get_size()

macb_dma_desc_get_size() does a switch on bp->hw_dma_cap and covers all
four cases: 0, 64B, PTP, 64B+PTP. It also covers the #ifndef
MACB_EXT_DESC separately, making it four codepaths.

Instead, notice the descriptor size grows with enabled features and use
plain if-statements on 64B and PTP flags.

Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 29 ++++++++---------------------
 1 file changed, 8 insertions(+), 21 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 33e99aab1dcb360a699d0e80762ef421001d19a1..7f74e280a3351ee7f961ff5ecd9550470b2e68eb 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -121,29 +121,16 @@ struct sifive_fu540_macb_mgmt {
  */
 static unsigned int macb_dma_desc_get_size(struct macb *bp)
 {
-#ifdef MACB_EXT_DESC
-	unsigned int desc_size;
+	unsigned int desc_size = sizeof(struct macb_dma_desc);

-	switch (bp->hw_dma_cap) {
-	case HW_DMA_CAP_64B:
-		desc_size = sizeof(struct macb_dma_desc)
-			+ sizeof(struct macb_dma_desc_64);
-		break;
-	case HW_DMA_CAP_PTP:
-		desc_size = sizeof(struct macb_dma_desc)
-			+ sizeof(struct macb_dma_desc_ptp);
-		break;
-	case HW_DMA_CAP_64B_PTP:
-		desc_size = sizeof(struct macb_dma_desc)
-			+ sizeof(struct macb_dma_desc_64)
-			+ sizeof(struct macb_dma_desc_ptp);
-		break;
-	default:
-		desc_size = sizeof(struct macb_dma_desc);
-	}
-	return desc_size;
+#ifdef MACB_EXT_DESC
+	if (bp->hw_dma_cap & HW_DMA_CAP_64B)
+		desc_size += sizeof(struct macb_dma_desc_64);
+	if (bp->hw_dma_cap & HW_DMA_CAP_PTP)
+		desc_size += sizeof(struct macb_dma_desc_ptp);
 #endif
-	return sizeof(struct macb_dma_desc);
+
+	return desc_size;
 }

 static unsigned int macb_adj_dma_desc_idx(struct macb *bp, unsigned int desc_idx)

-- 
2.51.0