Hi Jisheng,
Which baseline do you use?
It took me really lot of time to catch why RX broke after rebase from
LKv4.1 to LKv4.4. Between those two, in commit:
97303480753e ("arm64: Increase the max granular size")
L1_CACHE_BYTES for all ARMv8 platforms was increased to 128B and so
did NET_SKB_PAD.
And 128 is more than the maximum that can fit into packet offset
[11:8]@0x1400. In such case this correction is needed. Did it answer
your doubts?
Best regards,
Marcin
2016-12-01 12:26 GMT+01:00 Jisheng Zhang <[email protected]>:
> Hi Gregory, Marcin,
>
> On Wed, 30 Nov 2016 22:42:49 +0100 Gregory CLEMENT wrote:
>
>> From: Marcin Wojtas <[email protected]>
>>
>> Prepare the mvneta driver in order to be usable on the 64 bits platform
>> such as the Armada 3700.
>>
>> [[email protected]]: this patch was extract from a larger
>> one to ease review and maintenance.
>>
>> Signed-off-by: Marcin Wojtas <[email protected]>
>> Signed-off-by: Gregory CLEMENT <[email protected]>
>> ---
>> drivers/net/ethernet/marvell/mvneta.c | 17 ++++++++++++++++-
>> 1 file changed, 16 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/marvell/mvneta.c
>> b/drivers/net/ethernet/marvell/mvneta.c
>> index 92b9af14c352..8ef03fb69bcd 100644
>> --- a/drivers/net/ethernet/marvell/mvneta.c
>> +++ b/drivers/net/ethernet/marvell/mvneta.c
>> @@ -296,6 +296,12 @@
>> /* descriptor aligned size */
>> #define MVNETA_DESC_ALIGNED_SIZE 32
>>
>> +/* Number of bytes to be taken into account by HW when putting incoming data
>> + * to the buffers. It is needed in case NET_SKB_PAD exceeds maximum packet
>> + * offset supported in MVNETA_RXQ_CONFIG_REG(q) registers.
>
> We also brought up this driver on 64bit platforms, we doesn't have this
> patch. Maybe I'm wrong, I'm trying to understand why we need this
> modification. Let's assume the NET_SKB_PAD is 64B, we call
> mvneta_rxq_offset_set(pp, rxq, 64),
>
> {
> u32 val;
>
> val = mvreg_read(pp, MVNETA_RXQ_CONFIG_REG(rxq->id));
> val &= ~MVNETA_RXQ_PKT_OFFSET_ALL_MASK;
>
> /* Offset is in */
> val |= MVNETA_RXQ_PKT_OFFSET_MASK(offset >> 3);
> // then this will be "val |= 8;" it doesn't exceeds the max offset of
> MVNETA_RXQ_CONFIG_REG(q) register.
>
> Could you please kindly point out where I am wrong?
>
>> + */
>> +#define MVNETA_RX_PKT_OFFSET_CORRECTION 64
>> +
>> #define MVNETA_RX_PKT_SIZE(mtu) \
>> ALIGN((mtu) + MVNETA_MH_SIZE + MVNETA_VLAN_TAG_LEN + \
>> ETH_HLEN + ETH_FCS_LEN, \
>> @@ -416,6 +422,7 @@ struct mvneta_port {
>> u64 ethtool_stats[ARRAY_SIZE(mvneta_statistics)];
>>
>> u32 indir[MVNETA_RSS_LU_TABLE_SIZE];
>> + u16 rx_offset_correction;
>> };
>>
>> /* The mvneta_tx_desc and mvneta_rx_desc structures describe the
>> @@ -1807,6 +1814,7 @@ static int mvneta_rx_refill(struct mvneta_port *pp,
>> return -ENOMEM;
>> }
>>
>> + phys_addr += pp->rx_offset_correction;
>> mvneta_rx_desc_fill(rx_desc, phys_addr, data, rxq);
>> return 0;
>> }
>> @@ -2782,7 +2790,7 @@ static int mvneta_rxq_init(struct mvneta_port *pp,
>> mvreg_write(pp, MVNETA_RXQ_SIZE_REG(rxq->id), rxq->size);
>>
>> /* Set Offset */
>> - mvneta_rxq_offset_set(pp, rxq, NET_SKB_PAD);
>> + mvneta_rxq_offset_set(pp, rxq, NET_SKB_PAD - pp->rx_offset_correction);
>>
>> /* Set coalescing pkts and time */
>> mvneta_rx_pkts_coal_set(pp, rxq, rxq->pkts_coal);
>> @@ -4033,6 +4041,13 @@ static int mvneta_probe(struct platform_device *pdev)
>>
>> pp->rxq_def = rxq_def;
>>
>> + /* Set RX packet offset correction for platforms, whose
>> + * NET_SKB_PAD, exceeds 64B. It should be 64B for 64-bit
>> + * platforms and 0B for 32-bit ones.
>
> Even we need this patch, I'm not sure this last comment is correct or not.
> NET_SKB_PAD is defined as:
>
> #define NET_SKB_PAD max(32, L1_CACHE_BYTES)
>
> we have 64B cacheline 32bit platforms, on this platforms, the NET_SKB_PAD
> should be 64B as well.
>
> Thanks,
> Jisheng
