From: Nikita Yushchenko <nikita.yo...@cogentembedded.com> Sent: Wednesday,
November 30, 2016 2:35 AM
>To: David S. Miller <da...@davemloft.net>; Andy Duan
><fugang.d...@nxp.com>; Troy Kisky <troy.ki...@boundarydevices.com>;
>Andrew Lunn <and...@lunn.ch>; Eric Nelson <e...@nelint.com>; Philippe
>Reynes <trem...@gmail.com>; Johannes Berg <johan...@sipsolutions.net>;
>net...@vger.kernel.org
>Cc: Chris Healy <cphe...@gmail.com>; Fabio Estevam
><fabio.este...@nxp.com>; linux-kernel@vger.kernel.org; Nikita
>Yushchenko <nikita.yo...@cogentembedded.com>
>Subject: [patch net / RFC] net: fec: increase frame size limitation to
>actually
>available buffer
>
>Fec driver uses Rx buffers of 2k, but programs hardware to limit incoming
>frames to 1522 bytes. This raises issues when FEC device is used with DSA
>(since DSA tag can make frame larger), and also disallows manual sending and
>receiving larger frames.
>
>This patch removes the limitation, allowing Rx size up to entire buffer.
>At the same time possible Tx size is increased as well, because hardware uses
>the same register field to limit Rx and Tx.
>
>Signed-off-by: Nikita Yushchenko <nikita.yo...@cogentembedded.com>
>---
> drivers/net/ethernet/freescale/fec_main.c | 33 +++++++++++----------------
>----
> 1 file changed, 12 insertions(+), 21 deletions(-)
>
>diff --git a/drivers/net/ethernet/freescale/fec_main.c
>b/drivers/net/ethernet/freescale/fec_main.c
>index 73ac35780611..c09789a71024 100644
>--- a/drivers/net/ethernet/freescale/fec_main.c
>+++ b/drivers/net/ethernet/freescale/fec_main.c
>@@ -171,30 +171,12 @@ MODULE_PARM_DESC(macaddr, "FEC Ethernet
>MAC address"); #endif #endif /* CONFIG_M5272 */
>
>-/* The FEC stores dest/src/type/vlan, data, and checksum for receive
>packets.
>- */
>-#define PKT_MAXBUF_SIZE 1522
>-#define PKT_MINBUF_SIZE 64
>-#define PKT_MAXBLR_SIZE 1536
>-
> /* FEC receive acceleration */
> #define FEC_RACC_IPDIS (1 << 1)
> #define FEC_RACC_PRODIS (1 << 2)
> #define FEC_RACC_SHIFT16 BIT(7)
> #define FEC_RACC_OPTIONS (FEC_RACC_IPDIS | FEC_RACC_PRODIS)
>
>-/*
>- * The 5270/5271/5280/5282/532x RX control register also contains maximum
>frame
>- * size bits. Other FEC hardware does not, so we need to take that into
>- * account when setting it.
>- */
>-#if defined(CONFIG_M523x) || defined(CONFIG_M527x) ||
>defined(CONFIG_M528x) || \
>- defined(CONFIG_M520x) || defined(CONFIG_M532x) ||
>defined(CONFIG_ARM)
>-#define OPT_FRAME_SIZE (PKT_MAXBUF_SIZE << 16)
>-#else
>-#define OPT_FRAME_SIZE 0
>-#endif
>-
> /* FEC MII MMFR bits definition */
> #define FEC_MMFR_ST (1 << 30)
> #define FEC_MMFR_OP_READ (2 << 28)
>@@ -847,7 +829,8 @@ static void fec_enet_enable_ring(struct net_device
>*ndev)
> for (i = 0; i < fep->num_rx_queues; i++) {
> rxq = fep->rx_queue[i];
> writel(rxq->bd.dma, fep->hwp + FEC_R_DES_START(i));
>- writel(PKT_MAXBLR_SIZE, fep->hwp + FEC_R_BUFF_SIZE(i));
>+ writel(FEC_ENET_RX_FRSIZE - fep->rx_align,
>+ fep->hwp + FEC_R_BUFF_SIZE(i));
>
> /* enable DMA1/2 */
> if (i)
>@@ -895,9 +878,17 @@ fec_restart(struct net_device *ndev)
> struct fec_enet_private *fep = netdev_priv(ndev);
> u32 val;
> u32 temp_mac[2];
>- u32 rcntl = OPT_FRAME_SIZE | 0x04;
>+ u32 rcntl = 0x04;
> u32 ecntl = 0x2; /* ETHEREN */
>
>+ /* The 5270/5271/5280/5282/532x RX control register also contains
>+ * maximum frame * size bits. Other FEC hardware does not.
>+ */
>+#if defined(CONFIG_M523x) || defined(CONFIG_M527x) ||
>defined(CONFIG_M528x) || \
>+ defined(CONFIG_M520x) || defined(CONFIG_M532x) ||
>defined(CONFIG_ARM)
>+ rcntl |= (FEC_ENET_RX_FRSIZE - fep->rx_align) << 16; #endif
>+
> /* Whack a reset. We should wait for this.
> * For i.MX6SX SOC, enet use AXI bus, we use disable MAC
> * instead of reset MAC itself.
>@@ -953,7 +944,7 @@ fec_restart(struct net_device *ndev)
> else
> val &= ~FEC_RACC_OPTIONS;
> writel(val, fep->hwp + FEC_RACC);
>- writel(PKT_MAXBUF_SIZE, fep->hwp + FEC_FTRL);
>+ writel(FEC_ENET_RX_FRSIZE - fep->rx_align, fep->hwp +
>FEC_FTRL);
By the patch itself, it seems fine except MRBRn must be evenly divisible by 64.
But I think it is not necessary since the driver don't support jumbo frame.
> }
> #endif
>
>--
>2.1.4
