[PATCH net-next v1] net: stmmac: Programming sequence for VLAN packets with split header
Abhishek Chauhan (ABC)
quic_abchauha at quicinc.com
Wed Sep 4 19:05:22 PDT 2024
On 9/4/2024 6:12 PM, Sagar Cheluvegowda wrote:
>
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
>> index e0165358c4ac..dbd1be4e4a92 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
>> @@ -526,6 +526,17 @@ static void dwmac4_enable_sph(struct stmmac_priv *priv, void __iomem *ioaddr,
>> value |= GMAC_CONFIG_HDSMS_256; /* Segment max 256 bytes */
>> writel(value, ioaddr + GMAC_EXT_CONFIG);
>>
>> + /* Additional configuration to handle VLAN tagged packets */
>> + value = readl(ioaddr + GMAC_EXT_CFG1);
>> + value &= ~GMAC_CONFIG1_SPLM;
>> + /* Enable Split mode for header and payload at L2 */
>> + value |= GMAC_CONFIG1_SPLM_L2OFST_EN << GMAC_CONFIG1_SPLM_SHIFT;
>> + value &= ~GMAC_CONFIG1_SAVO;
>> + /* Enables the MAC to distinguish between tagged vs untagged pkts */
>> + value |= 4 << GMAC_CONFIG1_SAVO_SHIFT;
> I checked the data book internally and see SAVO bit is used to indicate the
> valueof the offset from the beginning of Length/Type field at which the header
> should be split, i see the length/type field remains to be 2bytes even in case
> of tagged packets may be you need to keep the value of this field to 2bytes as
> it was before but one thing which i am still not able to understand is that even
> with the value of this field configured to 4 i don't see any packet corruption
> issue, something which needs to be checked with HW folks.
Good catch Sagar. Let me check this internally and get back.
>> + value |= GMAC_CONFIG1_SAVE_EN;
>> + writel(value, ioaddr + GMAC_EXT_CFG1);
>> +
>> value = readl(ioaddr + DMA_CHAN_CONTROL(dwmac4_addrs, chan));
>> if (en)
>> value |= DMA_CONTROL_SPH;
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