net: fec: remove rx_align from fec_enet_private

The rx_align was introduced by the commit 41ef84ce4c72 ("net: fec: change
FEC alignment according to i.mx6 sx requirement"). Because the i.MX6 SX
requires RX buffer must be 64 bytes alignment.

Since the commit 95698ff6177b ("net: fec: using page pool to manage RX
buffers"), the address of the RX buffer is always the page address plus
FEC_ENET_XDP_HEADROOM which is 256 bytes, so the RX buffer is always
64-byte aligned. Therefore, rx_align has no effect since that commit,
and we can safely remove it.

In addition, to prevent future modifications to FEC_ENET_XDP_HEADROOM,
a BUILD_BUG_ON() test has been added to the driver, which ensures that
FEC_ENET_XDP_HEADROOM provides the required alignment.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
Link: https://patch.msgid.link/20251119025148.2817602-5-wei.fang@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index c5bbc2c16a4f9b1369b4b5cb49881427c2c8ab31..a25dca9c7d717ed011396014bb1054bfba61af31 100644 (file)
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -660,7 +660,6 @@ struct fec_enet_private {
        struct pm_qos_request pm_qos_req;
 
        unsigned int tx_align;
-       unsigned int rx_align;
 
        /* hw interrupt coalesce */
        unsigned int rx_pkts_itr;

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 6c19be0618ae0833c3875b1606371c9d5035acb8..c82be43b19abe398d11e6f7bfa2ed03326f19a5b 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -3438,6 +3438,19 @@ fec_enet_alloc_rxq_buffers(struct net_device *ndev, unsigned int queue)
                return err;
        }
 
+       /* Some platforms require the RX buffer must be 64 bytes alignment.
+        * Some platforms require 16 bytes alignment. And some platforms
+        * require 4 bytes alignment. But since the page pool have been
+        * introduced into the driver, the address of RX buffer is always
+        * the page address plus FEC_ENET_XDP_HEADROOM, and
+        * FEC_ENET_XDP_HEADROOM is 256 bytes. Therefore, this address can
+        * satisfy all platforms. To prevent future modifications to
+        * FEC_ENET_XDP_HEADROOM from ignoring this hardware limitation, a
+        * BUILD_BUG_ON() test has been added, which ensures that
+        * FEC_ENET_XDP_HEADROOM provides the required alignment.
+        */
+       BUILD_BUG_ON(FEC_ENET_XDP_HEADROOM & 0x3f);
+
        for (i = 0; i < rxq->bd.ring_size; i++) {
                page = page_pool_dev_alloc_pages(rxq->page_pool);
                if (!page)
@@ -4072,10 +4085,8 @@ static int fec_enet_init(struct net_device *ndev)
 
        WARN_ON(dsize != (1 << dsize_log2));
 #if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
-       fep->rx_align = 0xf;
        fep->tx_align = 0xf;
 #else
-       fep->rx_align = 0x3;
        fep->tx_align = 0x3;
 #endif
        fep->rx_pkts_itr = FEC_ITR_ICFT_DEFAULT;
@@ -4164,10 +4175,8 @@ static int fec_enet_init(struct net_device *ndev)
                fep->csum_flags |= FLAG_RX_CSUM_ENABLED;
        }
 
-       if (fep->quirks & FEC_QUIRK_HAS_MULTI_QUEUES) {
+       if (fep->quirks & FEC_QUIRK_HAS_MULTI_QUEUES)
                fep->tx_align = 0;
-               fep->rx_align = 0x3f;
-       }
 
        ndev->hw_features = ndev->features;