Re: [net-next 4/7] stmmac: allow mtu bigger than 1500 in case of normal desc (V3)
From: Giuseppe CAVALLARO <hidden>
Date: 2011-10-18 09:26:18
Hello Eric, On 10/18/2011 11:03 AM, Eric Dumazet wrote:
Le mardi 18 octobre 2011 à 10:42 +0200, Giuseppe CAVALLARO a écrit :quoted
This patch allows to set the mtu bigger than 1500 in case of normal descriptors. This is helping some SPEAr customers. Signed-off-by: Deepak SIKRI <redacted> Signed-off-by: Giuseppe Cavallaro <redacted> --- drivers/net/ethernet/stmicro/stmmac/norm_desc.c | 8 +++++++- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++-- 2 files changed, 9 insertions(+), 3 deletions(-)diff --git a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c index 029c2a2..e13226b 100644 --- a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c +++ b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c@@ -126,6 +126,7 @@ static void ndesc_init_rx_desc(struct dma_desc *p, unsigned int ring_size, for (i = 0; i < ring_size; i++) { p->des01.rx.own = 1; p->des01.rx.buffer1_size = BUF_SIZE_2KiB - 1; + p->des01.rx.buffer2_size = BUF_SIZE_2KiB - 1; if (i == ring_size - 1) p->des01.rx.end_ring = 1; if (disable_rx_ic)@@ -183,7 +184,12 @@ static void ndesc_prepare_tx_desc(struct dma_desc *p, int is_fs, int len, int csum_flag) { p->des01.tx.first_segment = is_fs; - p->des01.tx.buffer1_size = len; + + if (unlikely(len > BUF_SIZE_2KiB)) { + p->des01.etx.buffer1_size = BUF_SIZE_2KiB - 1; + p->des01.etx.buffer2_size = len - p->des01.etx.buffer1_size; + } else + p->des01.tx.buffer1_size = len; } static void ndesc_clear_tx_ic(struct dma_desc *p)diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index d0af002..622b7ac 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c@@ -1412,10 +1412,10 @@ static int stmmac_change_mtu(struct net_device *dev, int new_mtu) return -EBUSY; } - if (priv->plat->has_gmac) + if (priv->plat->enh_desc) max_mtu = JUMBO_LEN; else - max_mtu = ETH_DATA_LEN; + max_mtu = BUF_SIZE_4KiB; if ((new_mtu < 46) || (new_mtu > max_mtu)) { pr_err("%s: invalid MTU, max MTU is: %d\n", dev->name, max_mtu);Problem using big mtu around 4096 bytes is you end allocating (4096 +NET_SKB_PAD + NET_IP_ALIGN + sizeof(struct skb_shared_info) bytes -> 8192 bytes : order-1 pages
yes.
Maybe it would be better to limit your mtu to SKB_MAX_HEAD(NET_SKB_PAD), to have no more than one page per skb ?
ok! ;-)
quoted hunk ↗ jump to hunk
I would suggest changing netdev_alloc_skb_ip_align() done in init_dma_desc_rings() to use a variant allowing GFP_KERNEL allocations and allow your driver to load even in case of memory pressure.diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index c0ee6b6..8ec8057 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c@@ -458,11 +458,12 @@ static void init_dma_desc_rings(struct net_device *dev) for (i = 0; i < rxsize; i++) { struct dma_desc *p = priv->dma_rx + i; - skb = netdev_alloc_skb_ip_align(dev, bfsize); + skb = __netdev_alloc_skb(dev, bfsize + NET_IP_ALIGN, GFP_KERNEL); if (unlikely(skb == NULL)) { pr_err("%s: Rx init fails; skb is NULL\n", __func__); break; } + skb_reserve(skb, NET_IP_ALIGN); priv->rx_skbuff[i] = skb; priv->rx_skbuff_dma[i] = dma_map_single(priv->device, skb->data, bfsize, DMA_FROM_DEVICE);
Agree! I'm reviewing the patches and send all again. Many thanks Regards Peppe