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Subject: Re: [PATCH net-next] net: stmmac: set total length of the packet to
 be transmitted in TDES3
To: Giuseppe CAVALLARO <peppe.cavallaro@st.com>,
        Niklas Cassel <niklas.cassel@axis.com>, <Joao.Pinto@synopsys.com>
References: <20170410183329.28847-1-niklass@axis.com>
 <a50439b5-0e39-7d67-6034-9cf25ff947a2@st.com>
CC: <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Niklas Cassel <niklass@axis.com>
From: Alexandre Torgue <alexandre.torgue@st.com>
Message-ID: <76b6b77b-890e-77e8-5e82-f691982ebc34@st.com>
Date: Tue, 11 Apr 2017 09:20:33 +0200
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Hi,

On 04/11/2017 07:40 AM, Giuseppe CAVALLARO wrote:
> Hi Niklas
>
> patch looks ok for me, Alex any feedback?

It sounds good for me to.
>
> peppe
>
> On 4/10/2017 8:33 PM, Niklas Cassel wrote:
>> From: Niklas Cassel <niklas.cassel@axis.com>
>>
>> Field FL/TPL in register TDES3 is not correctly set on GMAC4.
>> TX appears to be functional on GMAC 4.10a even if this field is not set,
>> however, to avoid relying on undefined behavior, set the length in TDES3.
>>
>> The field has a different meaning depending on if the TSE bit in TDES3
>> is set or not (TSO). However, regardless of the TSE bit, the field is
>> not optional. The field is already set correctly when the TSE bit is set.
>>
>> Since there is no limit for the number of descriptors that can be
>> used for a single packet, the field should be set to the sum of
>> the buffers contained in:
>> [<desc with First Descriptor bit set> ... <desc n> ...
>> <desc with Last Descriptor bit set>], which should be equal to skb->len.
>>
>> Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
>> ---
>>   drivers/net/ethernet/stmicro/stmmac/chain_mode.c   | 6 +++---
>>   drivers/net/ethernet/stmicro/stmmac/common.h       | 2 +-
>>   drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c | 3 ++-
>>   drivers/net/ethernet/stmicro/stmmac/enh_desc.c     | 2 +-
>>   drivers/net/ethernet/stmicro/stmmac/norm_desc.c    | 2 +-
>>   drivers/net/ethernet/stmicro/stmmac/ring_mode.c    | 9 ++++++---
>>   drivers/net/ethernet/stmicro/stmmac/stmmac_main.c  | 5 +++--
>>   7 files changed, 17 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/chain_mode.c
>> b/drivers/net/ethernet/stmicro/stmmac/chain_mode.c
>> index 37881f81319e..e93c40b4631e 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/chain_mode.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/chain_mode.c
>> @@ -52,7 +52,7 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff
>> *skb, int csum)
>>       tx_q->tx_skbuff_dma[entry].len = bmax;
>>       /* do not close the descriptor and do not set own bit */
>>       priv->hw->desc->prepare_tx_desc(desc, 1, bmax, csum,
>> STMMAC_CHAIN_MODE,
>> -                    0, false);
>> +                    0, false, skb->len);
>>         while (len != 0) {
>>           tx_q->tx_skbuff[entry] = NULL;
>> @@ -70,7 +70,7 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff
>> *skb, int csum)
>>               tx_q->tx_skbuff_dma[entry].len = bmax;
>>               priv->hw->desc->prepare_tx_desc(desc, 0, bmax, csum,
>>                               STMMAC_CHAIN_MODE, 1,
>> -                            false);
>> +                            false, skb->len);
>>               len -= bmax;
>>               i++;
>>           } else {
>> @@ -85,7 +85,7 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff
>> *skb, int csum)
>>               /* last descriptor can be set now */
>>               priv->hw->desc->prepare_tx_desc(desc, 0, len, csum,
>>                               STMMAC_CHAIN_MODE, 1,
>> -                            true);
>> +                            true, skb->len);
>>               len = 0;
>>           }
>>       }
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h
>> b/drivers/net/ethernet/stmicro/stmmac/common.h
>> index 90d28bcad880..b7ce3fbb5375 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/common.h
>> +++ b/drivers/net/ethernet/stmicro/stmmac/common.h
>> @@ -373,7 +373,7 @@ struct stmmac_desc_ops {
>>       /* Invoked by the xmit function to prepare the tx descriptor */
>>       void (*prepare_tx_desc) (struct dma_desc *p, int is_fs, int len,
>>                    bool csum_flag, int mode, bool tx_own,
>> -                 bool ls);
>> +                 bool ls, unsigned int tot_pkt_len);
>>       void (*prepare_tso_tx_desc)(struct dma_desc *p, int is_fs, int
>> len1,
>>                       int len2, bool tx_own, bool ls,
>>                       unsigned int tcphdrlen,
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c
>> b/drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c
>> index 843ec69222ea..aa6476439aee 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c
>> @@ -304,12 +304,13 @@ static void dwmac4_rd_init_tx_desc(struct
>> dma_desc *p, int mode, int end)
>>     static void dwmac4_rd_prepare_tx_desc(struct dma_desc *p, int
>> is_fs, int len,
>>                         bool csum_flag, int mode, bool tx_own,
>> -                      bool ls)
>> +                      bool ls, unsigned int tot_pkt_len)
>>   {
>>       unsigned int tdes3 = le32_to_cpu(p->des3);
>>         p->des2 |= cpu_to_le32(len & TDES2_BUFFER1_SIZE_MASK);
>>   +    tdes3 |= tot_pkt_len & TDES3_PACKET_SIZE_MASK;
>>       if (is_fs)
>>           tdes3 |= TDES3_FIRST_DESCRIPTOR;
>>       else
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
>> b/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
>> index 323b59ec74a3..7546b3664113 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
>> @@ -315,7 +315,7 @@ static void enh_desc_release_tx_desc(struct
>> dma_desc *p, int mode)
>>     static void enh_desc_prepare_tx_desc(struct dma_desc *p, int
>> is_fs, int len,
>>                        bool csum_flag, int mode, bool tx_own,
>> -                     bool ls)
>> +                     bool ls, unsigned int tot_pkt_len)
>>   {
>>       unsigned int tdes0 = le32_to_cpu(p->des0);
>>   diff --git a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
>> b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
>> index efb818ebd55e..f817f8f36569 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
>> @@ -191,7 +191,7 @@ static void ndesc_release_tx_desc(struct dma_desc
>> *p, int mode)
>>     static void ndesc_prepare_tx_desc(struct dma_desc *p, int is_fs,
>> int len,
>>                     bool csum_flag, int mode, bool tx_own,
>> -                  bool ls)
>> +                  bool ls, unsigned int tot_pkt_len)
>>   {
>>       unsigned int tdes1 = le32_to_cpu(p->des1);
>>   diff --git a/drivers/net/ethernet/stmicro/stmmac/ring_mode.c
>> b/drivers/net/ethernet/stmicro/stmmac/ring_mode.c
>> index 31213e64513d..28e4b5d50ce6 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/ring_mode.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/ring_mode.c
>> @@ -59,7 +59,8 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff
>> *skb, int csum)
>>             desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
>>           priv->hw->desc->prepare_tx_desc(desc, 1, bmax, csum,
>> -                        STMMAC_RING_MODE, 0, false);
>> +                        STMMAC_RING_MODE, 0,
>> +                        false, skb->len);
>>           tx_q->tx_skbuff[entry] = NULL;
>>           entry = STMMAC_GET_ENTRY(entry, DMA_TX_SIZE);
>>   @@ -79,7 +80,8 @@ static int stmmac_jumbo_frm(void *p, struct
>> sk_buff *skb, int csum)
>>             desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
>>           priv->hw->desc->prepare_tx_desc(desc, 0, len, csum,
>> -                        STMMAC_RING_MODE, 1, true);
>> +                        STMMAC_RING_MODE, 1,
>> +                        true, skb->len);
>>       } else {
>>           des2 = dma_map_single(priv->device, skb->data,
>>                         nopaged_len, DMA_TO_DEVICE);
>> @@ -91,7 +93,8 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff
>> *skb, int csum)
>>           tx_q->tx_skbuff_dma[entry].is_jumbo = true;
>>           desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
>>           priv->hw->desc->prepare_tx_desc(desc, 1, nopaged_len, csum,
>> -                        STMMAC_RING_MODE, 0, true);
>> +                        STMMAC_RING_MODE, 0,
>> +                        true, skb->len);
>>       }
>>         tx_q->cur_tx = entry;
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>> b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>> index a89f76b27ea2..5c1ebc70bebd 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>> @@ -3033,7 +3033,8 @@ static netdev_tx_t stmmac_xmit(struct sk_buff
>> *skb, struct net_device *dev)
>>             /* Prepare the descriptor and set the own bit too */
>>           priv->hw->desc->prepare_tx_desc(desc, 0, len, csum_insertion,
>> -                        priv->mode, 1, last_segment);
>> +                        priv->mode, 1, last_segment,
>> +                        skb->len);
>>       }
>>         entry = STMMAC_GET_ENTRY(entry, DMA_TX_SIZE);
>> @@ -3116,7 +3117,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff
>> *skb, struct net_device *dev)
>>           /* Prepare the first descriptor setting the OWN bit too */
>>           priv->hw->desc->prepare_tx_desc(first, 1, nopaged_len,
>>                           csum_insertion, priv->mode, 1,
>> -                        last_segment);
>> +                        last_segment, skb->len);
>>             /* The own bit must be the latest setting done when
>> prepare the
>>            * descriptor and then barrier is needed to make sure that
>
>