[PATCH net-next v6 0/4] net: macb: WOL enhancements

[PATCH net-next v6 0/4] net: macb: WOL enhancements

[Vineeth Karumanchi]

- Add provisioning for queue tie-off and queue disable during suspend.
- Add support for ARP packet types to WoL.
- Advertise WoL attributes by default.
- Extend MACB supported WoL modes to the PHY supported WoL modes.
- Deprecate magic-packet property.

Changes in V6:
- Use rcu_access_pointer() instead of rcu_dereference()
- Add conditional check on __in_dev_get_rcu() return pointer

Changes in V5:
- Update comment and error message.
v5 link : https://lore.kernel.org/netdev/20240611162827.887162-1-vineeth.karumanchi@amd.com/

Changes in V4:
- Extend MACB supported wol modes to the PHY supported modes.
- Drop previous ACK from v2 series on 4/4 patch for further review.
v4 link : https://lore.kernel.org/lkml/20240610053936.622237-1-vineeth.karumanchi@amd.com/

Changes in V3:
- Advertise WOL by default.
- Drop previous ACK for further review.
v3 link : https://lore.kernel.org/netdev/20240605102457.4050539-1-vineeth.karumanchi@amd.com/

Changes in v2:
- Re-implement WOL using CAPS instead of device-tree attribute.
- Deprecate device-tree "magic-packet" property.
- Sorted CAPS values.
- New Bit fields inline with existing implementation.
- Optimize code.
- Fix sparse warnings.
- Addressed minor review comments.
v2 link : https://lore.kernel.org/netdev/20240222153848.2374782-1-vineeth.karumanchi@amd.com/

v1 link : https://lore.kernel.org/lkml/20240130104845.3995341-1-vineeth.karumanchi@amd.com/#t


Vineeth Karumanchi (4):
  net: macb: queue tie-off or disable during WOL suspend
  net: macb: Enable queue disable
  net: macb: Add ARP support to WOL
  dt-bindings: net: cdns,macb: Deprecate magic-packet property

 .../devicetree/bindings/net/cdns,macb.yaml    |   1 +
 drivers/net/ethernet/cadence/macb.h           |   8 ++
 drivers/net/ethernet/cadence/macb_main.c      | 122 +++++++++++++-----
 3 files changed, 101 insertions(+), 30 deletions(-)

-- 
2.34.1

[PATCH net-next v6 1/4] net: macb: queue tie-off or disable during WOL suspend

[Vineeth Karumanchi]

When GEM is used as a wake device, it is not mandatory for the RX DMA
to be active. The RX engine in IP only needs to receive and identify
a wake packet through an interrupt. The wake packet is of no further
significance; hence, it is not required to be copied into memory.
By disabling RX DMA during suspend, we can avoid unnecessary DMA
processing of any incoming traffic.

During suspend, perform either of the below operations:

- tie-off/dummy descriptor: Disable unused queues by connecting
  them to a looped descriptor chain without free slots.

- queue disable: The newer IP version allows disabling individual queues.

Co-developed-by: Harini Katakam <harini.katakam@amd.com>
Signed-off-by: Harini Katakam <harini.katakam@amd.com>
Signed-off-by: Vineeth Karumanchi <vineeth.karumanchi@amd.com>
---
 drivers/net/ethernet/cadence/macb.h      |  7 +++
 drivers/net/ethernet/cadence/macb_main.c | 60 ++++++++++++++++++++++--
 2 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index aa5700ac9c00..50cd35ef21ad 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -645,6 +645,10 @@
 #define GEM_T2OFST_OFFSET			0 /* offset value */
 #define GEM_T2OFST_SIZE				7
 
+/* Bitfields in queue pointer registers */
+#define MACB_QUEUE_DISABLE_OFFSET		0 /* disable queue */
+#define MACB_QUEUE_DISABLE_SIZE			1
+
 /* Offset for screener type 2 compare values (T2CMPOFST).
  * Note the offset is applied after the specified point,
  * e.g. GEM_T2COMPOFST_ETYPE denotes the EtherType field, so an offset
@@ -733,6 +737,7 @@
 #define MACB_CAPS_NEEDS_RSTONUBR		0x00000100
 #define MACB_CAPS_MIIONRGMII			0x00000200
 #define MACB_CAPS_NEED_TSUCLK			0x00000400
+#define MACB_CAPS_QUEUE_DISABLE			0x00000800
 #define MACB_CAPS_PCS				0x01000000
 #define MACB_CAPS_HIGH_SPEED			0x02000000
 #define MACB_CAPS_CLK_HW_CHG			0x04000000
@@ -1254,6 +1259,8 @@ struct macb {
 	u32	(*macb_reg_readl)(struct macb *bp, int offset);
 	void	(*macb_reg_writel)(struct macb *bp, int offset, u32 value);
 
+	struct macb_dma_desc	*rx_ring_tieoff;
+	dma_addr_t		rx_ring_tieoff_dma;
 	size_t			rx_buffer_size;
 
 	unsigned int		rx_ring_size;
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 241ce9a2fa99..9fc8c5a82bf8 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -2477,6 +2477,12 @@ static void macb_free_consistent(struct macb *bp)
 	unsigned int q;
 	int size;
 
+	if (bp->rx_ring_tieoff) {
+		dma_free_coherent(&bp->pdev->dev, macb_dma_desc_get_size(bp),
+				  bp->rx_ring_tieoff, bp->rx_ring_tieoff_dma);
+		bp->rx_ring_tieoff = NULL;
+	}
+
 	bp->macbgem_ops.mog_free_rx_buffers(bp);
 
 	for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) {
@@ -2568,6 +2574,16 @@ static int macb_alloc_consistent(struct macb *bp)
 	if (bp->macbgem_ops.mog_alloc_rx_buffers(bp))
 		goto out_err;
 
+	/* Required for tie off descriptor for PM cases */
+	if (!(bp->caps & MACB_CAPS_QUEUE_DISABLE)) {
+		bp->rx_ring_tieoff = dma_alloc_coherent(&bp->pdev->dev,
+							macb_dma_desc_get_size(bp),
+							&bp->rx_ring_tieoff_dma,
+							GFP_KERNEL);
+		if (!bp->rx_ring_tieoff)
+			goto out_err;
+	}
+
 	return 0;
 
 out_err:
@@ -2575,6 +2591,19 @@ static int macb_alloc_consistent(struct macb *bp)
 	return -ENOMEM;
 }
 
+static void macb_init_tieoff(struct macb *bp)
+{
+	struct macb_dma_desc *desc = bp->rx_ring_tieoff;
+
+	if (bp->caps & MACB_CAPS_QUEUE_DISABLE)
+		return;
+	/* Setup a wrapping descriptor with no free slots
+	 * (WRAP and USED) to tie off/disable unused RX queues.
+	 */
+	macb_set_addr(bp, desc, MACB_BIT(RX_WRAP) | MACB_BIT(RX_USED));
+	desc->ctrl = 0;
+}
+
 static void gem_init_rings(struct macb *bp)
 {
 	struct macb_queue *queue;
@@ -2598,6 +2627,7 @@ static void gem_init_rings(struct macb *bp)
 		gem_rx_refill(queue);
 	}
 
+	macb_init_tieoff(bp);
 }
 
 static void macb_init_rings(struct macb *bp)
@@ -2615,6 +2645,8 @@ static void macb_init_rings(struct macb *bp)
 	bp->queues[0].tx_head = 0;
 	bp->queues[0].tx_tail = 0;
 	desc->ctrl |= MACB_BIT(TX_WRAP);
+
+	macb_init_tieoff(bp);
 }
 
 static void macb_reset_hw(struct macb *bp)
@@ -5215,6 +5247,7 @@ static int __maybe_unused macb_suspend(struct device *dev)
 	unsigned long flags;
 	unsigned int q;
 	int err;
+	u32 tmp;
 
 	if (!device_may_wakeup(&bp->dev->dev))
 		phy_exit(bp->sgmii_phy);
@@ -5224,17 +5257,38 @@ static int __maybe_unused macb_suspend(struct device *dev)
 
 	if (bp->wol & MACB_WOL_ENABLED) {
 		spin_lock_irqsave(&bp->lock, flags);
-		/* Flush all status bits */
-		macb_writel(bp, TSR, -1);
-		macb_writel(bp, RSR, -1);
+
+		/* Disable Tx and Rx engines before  disabling the queues,
+		 * this is mandatory as per the IP spec sheet
+		 */
+		tmp = macb_readl(bp, NCR);
+		macb_writel(bp, NCR, tmp & ~(MACB_BIT(TE) | MACB_BIT(RE)));
 		for (q = 0, queue = bp->queues; q < bp->num_queues;
 		     ++q, ++queue) {
+			/* Disable RX queues */
+			if (bp->caps & MACB_CAPS_QUEUE_DISABLE) {
+				queue_writel(queue, RBQP, MACB_BIT(QUEUE_DISABLE));
+			} else {
+				/* Tie off RX queues */
+				queue_writel(queue, RBQP,
+					     lower_32_bits(bp->rx_ring_tieoff_dma));
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
+				queue_writel(queue, RBQPH,
+					     upper_32_bits(bp->rx_ring_tieoff_dma));
+#endif
+			}
 			/* Disable all interrupts */
 			queue_writel(queue, IDR, -1);
 			queue_readl(queue, ISR);
 			if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
 				queue_writel(queue, ISR, -1);
 		}
+		/* Enable Receive engine */
+		macb_writel(bp, NCR, tmp | MACB_BIT(RE));
+		/* Flush all status bits */
+		macb_writel(bp, TSR, -1);
+		macb_writel(bp, RSR, -1);
+
 		/* Change interrupt handler and
 		 * Enable WoL IRQ on queue 0
 		 */
-- 
2.34.1

[PATCH net-next v6 2/4] net: macb: Enable queue disable

[Vineeth Karumanchi]

Enable queue disable for Versal devices.

Signed-off-by: Vineeth Karumanchi <vineeth.karumanchi@amd.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/ethernet/cadence/macb_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 9fc8c5a82bf8..4007b291526f 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -4949,7 +4949,8 @@ static const struct macb_config sama7g5_emac_config = {
 
 static const struct macb_config versal_config = {
 	.caps = MACB_CAPS_GIGABIT_MODE_AVAILABLE | MACB_CAPS_JUMBO |
-		MACB_CAPS_GEM_HAS_PTP | MACB_CAPS_BD_RD_PREFETCH | MACB_CAPS_NEED_TSUCLK,
+		MACB_CAPS_GEM_HAS_PTP | MACB_CAPS_BD_RD_PREFETCH | MACB_CAPS_NEED_TSUCLK |
+		MACB_CAPS_QUEUE_DISABLE,
 	.dma_burst_length = 16,
 	.clk_init = macb_clk_init,
 	.init = init_reset_optional,
-- 
2.34.1

[PATCH net-next v6 3/4] net: macb: Add ARP support to WOL

[Vineeth Karumanchi]

Extend wake-on LAN support with an ARP packet.

Currently, if PHY supports WOL, ethtool ignores the modes supported
by MACB. This change extends the WOL modes with MACB supported modes.

Advertise wake-on LAN supported modes by default without relying on
dt node. By default, wake-on LAN will be in disabled state.
Using ethtool, users can enable/disable or choose packet types.

For wake-on LAN via ARP, ensure the IP address is assigned and
report an error otherwise.

Co-developed-by: Harini Katakam <harini.katakam@amd.com>
Signed-off-by: Harini Katakam <harini.katakam@amd.com>
Signed-off-by: Vineeth Karumanchi <vineeth.karumanchi@amd.com>
---
Changes in V6:
- Use rcu_access_pointer() instead of rcu_dereference()
- Add conditional check on __in_dev_get_rcu() return pointer
---
 drivers/net/ethernet/cadence/macb.h      |  1 +
 drivers/net/ethernet/cadence/macb_main.c | 59 +++++++++++++-----------
 2 files changed, 34 insertions(+), 26 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 50cd35ef21ad..122663ff7834 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -1306,6 +1306,7 @@ struct macb {
 	unsigned int		jumbo_max_len;
 
 	u32			wol;
+	u32			wolopts;
 
 	/* holds value of rx watermark value for pbuf_rxcutthru register */
 	u32			rx_watermark;
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 4007b291526f..8937445549a9 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -38,6 +38,7 @@
 #include <linux/ptp_classify.h>
 #include <linux/reset.h>
 #include <linux/firmware/xlnx-zynqmp.h>
+#include <linux/inetdevice.h>
 #include "macb.h"
 
 /* This structure is only used for MACB on SiFive FU540 devices */
@@ -84,8 +85,7 @@ struct sifive_fu540_macb_mgmt {
 #define GEM_MTU_MIN_SIZE	ETH_MIN_MTU
 #define MACB_NETIF_LSO		NETIF_F_TSO
 
-#define MACB_WOL_HAS_MAGIC_PACKET	(0x1 << 0)
-#define MACB_WOL_ENABLED		(0x1 << 1)
+#define MACB_WOL_ENABLED		(0x1 << 0)
 
 #define HS_SPEED_10000M			4
 #define MACB_SERDES_RATE_10G		1
@@ -3278,13 +3278,11 @@ static void macb_get_wol(struct net_device *netdev, struct ethtool_wolinfo *wol)
 {
 	struct macb *bp = netdev_priv(netdev);
 
-	if (bp->wol & MACB_WOL_HAS_MAGIC_PACKET) {
-		phylink_ethtool_get_wol(bp->phylink, wol);
-		wol->supported |= WAKE_MAGIC;
+	phylink_ethtool_get_wol(bp->phylink, wol);
+	wol->supported |= (WAKE_MAGIC | WAKE_ARP);
 
-		if (bp->wol & MACB_WOL_ENABLED)
-			wol->wolopts |= WAKE_MAGIC;
-	}
+	/* Add macb wolopts to phy wolopts */
+	wol->wolopts |= bp->wolopts;
 }
 
 static int macb_set_wol(struct net_device *netdev, struct ethtool_wolinfo *wol)
@@ -3294,22 +3292,15 @@ static int macb_set_wol(struct net_device *netdev, struct ethtool_wolinfo *wol)
 
 	/* Pass the order to phylink layer */
 	ret = phylink_ethtool_set_wol(bp->phylink, wol);
-	/* Don't manage WoL on MAC if handled by the PHY
-	 * or if there's a failure in talking to the PHY
-	 */
-	if (!ret || ret != -EOPNOTSUPP)
+	/* Don't manage WoL on MAC, if PHY set_wol() fails */
+	if (ret && ret != -EOPNOTSUPP)
 		return ret;
 
-	if (!(bp->wol & MACB_WOL_HAS_MAGIC_PACKET) ||
-	    (wol->wolopts & ~WAKE_MAGIC))
-		return -EOPNOTSUPP;
-
-	if (wol->wolopts & WAKE_MAGIC)
-		bp->wol |= MACB_WOL_ENABLED;
-	else
-		bp->wol &= ~MACB_WOL_ENABLED;
+	bp->wolopts = (wol->wolopts & WAKE_MAGIC) ? WAKE_MAGIC : 0;
+	bp->wolopts |= (wol->wolopts & WAKE_ARP) ? WAKE_ARP : 0;
+	bp->wol = (wol->wolopts) ? MACB_WOL_ENABLED : 0;
 
-	device_set_wakeup_enable(&bp->pdev->dev, bp->wol & MACB_WOL_ENABLED);
+	device_set_wakeup_enable(&bp->pdev->dev, bp->wol);
 
 	return 0;
 }
@@ -5086,9 +5077,7 @@ static int macb_probe(struct platform_device *pdev)
 		bp->max_tx_length = GEM_MAX_TX_LEN;
 
 	bp->wol = 0;
-	if (of_property_read_bool(np, "magic-packet"))
-		bp->wol |= MACB_WOL_HAS_MAGIC_PACKET;
-	device_set_wakeup_capable(&pdev->dev, bp->wol & MACB_WOL_HAS_MAGIC_PACKET);
+	device_set_wakeup_capable(&pdev->dev, 1);
 
 	bp->usrio = macb_config->usrio;
 
@@ -5244,7 +5233,9 @@ static int __maybe_unused macb_suspend(struct device *dev)
 {
 	struct net_device *netdev = dev_get_drvdata(dev);
 	struct macb *bp = netdev_priv(netdev);
+	struct in_ifaddr *ifa = NULL;
 	struct macb_queue *queue;
+	struct in_device *idev;
 	unsigned long flags;
 	unsigned int q;
 	int err;
@@ -5257,6 +5248,14 @@ static int __maybe_unused macb_suspend(struct device *dev)
 		return 0;
 
 	if (bp->wol & MACB_WOL_ENABLED) {
+		/* Check for IP address in WOL ARP mode */
+		idev = __in_dev_get_rcu(bp->dev);
+		if (idev && idev->ifa_list)
+			ifa = rcu_access_pointer(idev->ifa_list);
+		if ((bp->wolopts & WAKE_ARP) && !ifa) {
+			netdev_err(netdev, "IP address not assigned as required by WoL walk ARP\n");
+			return -EOPNOTSUPP;
+		}
 		spin_lock_irqsave(&bp->lock, flags);
 
 		/* Disable Tx and Rx engines before  disabling the queues,
@@ -5290,6 +5289,14 @@ static int __maybe_unused macb_suspend(struct device *dev)
 		macb_writel(bp, TSR, -1);
 		macb_writel(bp, RSR, -1);
 
+		tmp = (bp->wolopts & WAKE_MAGIC) ? MACB_BIT(MAG) : 0;
+		if (bp->wolopts & WAKE_ARP) {
+			tmp |= MACB_BIT(ARP);
+			/* write IP address into register */
+			tmp |= MACB_BFEXT(IP,
+					 (__force u32)(cpu_to_be32p((uint32_t *)&ifa->ifa_local)));
+		}
+
 		/* Change interrupt handler and
 		 * Enable WoL IRQ on queue 0
 		 */
@@ -5305,7 +5312,7 @@ static int __maybe_unused macb_suspend(struct device *dev)
 				return err;
 			}
 			queue_writel(bp->queues, IER, GEM_BIT(WOL));
-			gem_writel(bp, WOL, MACB_BIT(MAG));
+			gem_writel(bp, WOL, tmp);
 		} else {
 			err = devm_request_irq(dev, bp->queues[0].irq, macb_wol_interrupt,
 					       IRQF_SHARED, netdev->name, bp->queues);
@@ -5317,7 +5324,7 @@ static int __maybe_unused macb_suspend(struct device *dev)
 				return err;
 			}
 			queue_writel(bp->queues, IER, MACB_BIT(WOL));
-			macb_writel(bp, WOL, MACB_BIT(MAG));
+			macb_writel(bp, WOL, tmp);
 		}
 		spin_unlock_irqrestore(&bp->lock, flags);
 
-- 
2.34.1

[PATCH net-next v6 4/4] dt-bindings: net: cdns,macb: Deprecate magic-packet property

[Vineeth Karumanchi]

WOL modes such as magic-packet should be an OS policy.
By default, advertise supported modes and use ethtool to activate
the required mode.

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Vineeth Karumanchi <vineeth.karumanchi@amd.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
 Documentation/devicetree/bindings/net/cdns,macb.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/net/cdns,macb.yaml b/Documentation/devicetree/bindings/net/cdns,macb.yaml
index 2c71e2cf3a2f..3c30dd23cd4e 100644
--- a/Documentation/devicetree/bindings/net/cdns,macb.yaml
+++ b/Documentation/devicetree/bindings/net/cdns,macb.yaml
@@ -146,6 +146,7 @@ patternProperties:
 
       magic-packet:
         type: boolean
+        deprecated: true
         description:
           Indicates that the hardware supports waking up via magic packet.
 
-- 
2.34.1

Re: [PATCH net-next v6 3/4] net: macb: Add ARP support to WOL

[Simon Horman]

On Mon, Jun 17, 2024 at 12:34:12PM +0530, Vineeth Karumanchi wrote:
> Extend wake-on LAN support with an ARP packet.
> 
> Currently, if PHY supports WOL, ethtool ignores the modes supported
> by MACB. This change extends the WOL modes with MACB supported modes.
> 
> Advertise wake-on LAN supported modes by default without relying on
> dt node. By default, wake-on LAN will be in disabled state.
> Using ethtool, users can enable/disable or choose packet types.
> 
> For wake-on LAN via ARP, ensure the IP address is assigned and
> report an error otherwise.
> 
> Co-developed-by: Harini Katakam <harini.katakam@amd.com>
> Signed-off-by: Harini Katakam <harini.katakam@amd.com>
> Signed-off-by: Vineeth Karumanchi <vineeth.karumanchi@amd.com>

...

> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c

...

> @@ -84,8 +85,7 @@ struct sifive_fu540_macb_mgmt {
>  #define GEM_MTU_MIN_SIZE	ETH_MIN_MTU
>  #define MACB_NETIF_LSO		NETIF_F_TSO
>  
> -#define MACB_WOL_HAS_MAGIC_PACKET	(0x1 << 0)
> -#define MACB_WOL_ENABLED		(0x1 << 1)
> +#define MACB_WOL_ENABLED		(0x1 << 0)


nit: BIT() could be used here

>  
>  #define HS_SPEED_10000M			4
>  #define MACB_SERDES_RATE_10G		1

...

> @@ -5290,6 +5289,14 @@ static int __maybe_unused macb_suspend(struct device *dev)
>  		macb_writel(bp, TSR, -1);
>  		macb_writel(bp, RSR, -1);
>  
> +		tmp = (bp->wolopts & WAKE_MAGIC) ? MACB_BIT(MAG) : 0;
> +		if (bp->wolopts & WAKE_ARP) {
> +			tmp |= MACB_BIT(ARP);
> +			/* write IP address into register */
> +			tmp |= MACB_BFEXT(IP,
> +					 (__force u32)(cpu_to_be32p((uint32_t *)&ifa->ifa_local)));

Hi Vineeth and Harini,

I guess I must be reading this wrong, beause I am confused
by the intent of the endeness handling above.

* ifa->ifa_local is a 32-bit big-endian value

* It's address is cast to a 32-bit host-endian pointer

  nit: I think u32 would be preferable to uint32_t; this is kernel code.

* The value at this address is then converted to a host byte order value.

  nit: Why is cpu_to_be32p() used here instead of the more commonly used
       cpu_to_be32() ?

  More importantly, why is a host byte order value being converted from
  big-endian to host byte order?

* The value returned by cpu_to_be32p, which is big-endian, because
  that is what that function does, is then cast to host-byte order.


So overall we have:

1. Cast from big endian to host byte order
2. Conversion from host byte order to big endian
   (a bytes-swap on litte endian hosts; no-op on big endian hosts)
3. Cast from big endian to host byte oder

All three of these steps seem to warrant explanation.
And the combination is confusing to say the least.


> +		}
> +
>  		/* Change interrupt handler and
>  		 * Enable WoL IRQ on queue 0

...

Re: [PATCH net-next v6 3/4] net: macb: Add ARP support to WOL

[Karumanchi, Vineeth]

Hi Simon,

On 6/18/2024 4:26 PM, Simon Horman wrote:
> On Mon, Jun 17, 2024 at 12:34:12PM +0530, Vineeth Karumanchi wrote:
>> Extend wake-on LAN support with an ARP packet.

...

> ...
> 
>> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> 
> ...
> 
>> @@ -84,8 +85,7 @@ struct sifive_fu540_macb_mgmt {
>>   #define GEM_MTU_MIN_SIZE	ETH_MIN_MTU
>>   #define MACB_NETIF_LSO		NETIF_F_TSO
>>   
>> -#define MACB_WOL_HAS_MAGIC_PACKET	(0x1 << 0)
>> -#define MACB_WOL_ENABLED		(0x1 << 1)
>> +#define MACB_WOL_ENABLED		(0x1 << 0)
> 
> 
> nit: BIT() could be used here
> 

OK.

>>   
>>   #define HS_SPEED_10000M			4
>>   #define MACB_SERDES_RATE_10G		1
> 
> ...
> 
>> @@ -5290,6 +5289,14 @@ static int __maybe_unused macb_suspend(struct device *dev)
>>   		macb_writel(bp, TSR, -1);
>>   		macb_writel(bp, RSR, -1);
>>   
>> +		tmp = (bp->wolopts & WAKE_MAGIC) ? MACB_BIT(MAG) : 0;
>> +		if (bp->wolopts & WAKE_ARP) {
>> +			tmp |= MACB_BIT(ARP);
>> +			/* write IP address into register */
>> +			tmp |= MACB_BFEXT(IP,
>> +					 (__force u32)(cpu_to_be32p((uint32_t *)&ifa->ifa_local)));
> 
> Hi Vineeth and Harini,
> 
> I guess I must be reading this wrong, beause I am confused
> by the intent of the endeness handling above.
> 
> * ifa->ifa_local is a 32-bit big-endian value
> 
> * It's address is cast to a 32-bit host-endian pointer
> 
>    nit: I think u32 would be preferable to uint32_t; this is kernel code.
> 
> * The value at this address is then converted to a host byte order value.
> 
>    nit: Why is cpu_to_be32p() used here instead of the more commonly used
>         cpu_to_be32() ?
> 
>    More importantly, why is a host byte order value being converted from
>    big-endian to host byte order?
> 
> * The value returned by cpu_to_be32p, which is big-endian, because
>    that is what that function does, is then cast to host-byte order.
> 
> 
> So overall we have:
> 
> 1. Cast from big endian to host byte order
> 2. Conversion from host byte order to big endian
>     (a bytes-swap on litte endian hosts; no-op on big endian hosts)
> 3. Cast from big endian to host byte oder
> 
> All three of these steps seem to warrant explanation.
> And the combination is confusing to say the least.
> 

tmp |= MACB_BFEXT(IP, be32_to_cpu(ifa->ifa_local));

The above snippet will address above points.
Consider the ip address is : 11.11.70.78

1. ifa->ifa_local : returns be32 -> 0x4E460b0b
2. be32_to_cpu(ifa->ifa_local) : converts be32 to host byte order u32: 
0x0b0b464e

There are no sparse errors as well.
I will make the change, please let me know your suggestions/thoughts.

Thanks
🙏 vineeth

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Re: [PATCH net-next v6 3/4] net: macb: Add ARP support to WOL

[Simon Horman]

Hi Vineeth,

On Thu, Jun 20, 2024 at 09:29:01PM +0530, Karumanchi, Vineeth wrote:
> Hi Simon,
> 
> On 6/18/2024 4:26 PM, Simon Horman wrote:
> > On Mon, Jun 17, 2024 at 12:34:12PM +0530, Vineeth Karumanchi wrote:

...

> > > @@ -5290,6 +5289,14 @@ static int __maybe_unused macb_suspend(struct device *dev)
> > >   		macb_writel(bp, TSR, -1);
> > >   		macb_writel(bp, RSR, -1);
> > > +		tmp = (bp->wolopts & WAKE_MAGIC) ? MACB_BIT(MAG) : 0;
> > > +		if (bp->wolopts & WAKE_ARP) {
> > > +			tmp |= MACB_BIT(ARP);
> > > +			/* write IP address into register */
> > > +			tmp |= MACB_BFEXT(IP,
> > > +					 (__force u32)(cpu_to_be32p((uint32_t *)&ifa->ifa_local)));
> > 
> > Hi Vineeth and Harini,
> > 
> > I guess I must be reading this wrong, beause I am confused
> > by the intent of the endeness handling above.
> > 
> > * ifa->ifa_local is a 32-bit big-endian value
> > 
> > * It's address is cast to a 32-bit host-endian pointer
> > 
> >    nit: I think u32 would be preferable to uint32_t; this is kernel code.
> > 
> > * The value at this address is then converted to a host byte order value.
> > 
> >    nit: Why is cpu_to_be32p() used here instead of the more commonly used
> >         cpu_to_be32() ?
> > 
> >    More importantly, why is a host byte order value being converted from
> >    big-endian to host byte order?
> > 
> > * The value returned by cpu_to_be32p, which is big-endian, because
> >    that is what that function does, is then cast to host-byte order.
> > 
> > 
> > So overall we have:
> > 
> > 1. Cast from big endian to host byte order
> > 2. Conversion from host byte order to big endian
> >     (a bytes-swap on litte endian hosts; no-op on big endian hosts)
> > 3. Cast from big endian to host byte oder
> > 
> > All three of these steps seem to warrant explanation.
> > And the combination is confusing to say the least.
> > 
> 
> tmp |= MACB_BFEXT(IP, be32_to_cpu(ifa->ifa_local));
> 
> The above snippet will address above points.
> Consider the ip address is : 11.11.70.78
> 
> 1. ifa->ifa_local : returns be32 -> 0x4E460b0b
> 2. be32_to_cpu(ifa->ifa_local) : converts be32 to host byte order u32:
> 0x0b0b464e
> 
> There are no sparse errors as well.
> I will make the change, please let me know your suggestions/thoughts.

Thanks for your response, your proposal looks good to me.