Subject: Re: [PATCH 1/2] net: emac: implement 802.1Q VLAN TX tagging support

From: Florian Fainelli <[email-masked]>
Date: Wed, 17 Oct 2018 13:09:10 -0700

On 10/17/2018 01:08 PM, Florian Fainelli wrote:
> On 10/17/2018 12:53 PM, Christian Lamparter wrote:
>> As per' APM82181 Embedded Processor User Manual 26.1 EMAC Features:
>> VLAN:
>>  - Support for VLAN tag ID in compliance with IEEE 802.3ac.
>>  - VLAN tag insertion or replacement for transmit packets
>>
>> This patch completes the missing code for the VLAN tx tagging
>> support, as the the EMAC_MR1_VLE was already enabled.
>>
>> Signed-off-by: Christian Lamparter <[email-masked]>
>> ---
>>  drivers/net/ethernet/ibm/emac/core.c | 32 ++++++++++++++++++++++++----
>>  drivers/net/ethernet/ibm/emac/core.h |  6 +++++-
>>  2 files changed, 33 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/ibm/emac/core.c b/drivers/net/ethernet/ibm/emac/core.c
>> index 760b2ad8e295..be560f9031f4 100644
>> --- a/drivers/net/ethernet/ibm/emac/core.c
>> +++ b/drivers/net/ethernet/ibm/emac/core.c
>> @@ -37,6 +37,7 @@
>>  #include <linux/ethtool.h>
>>  #include <linux/mii.h>
>>  #include <linux/bitops.h>
>> +#include <linux/if_vlan.h>
>>  #include <linux/workqueue.h>
>>  #include <linux/of.h>
>>  #include <linux/of_address.h>
>> @@ -674,7 +675,7 @@ static int emac_configure(struct emac_instance *dev)
>>  		 ndev->dev_addr[5]);
>>  
>>  	/* VLAN Tag Protocol ID */
>> -	out_be32(&p->vtpid, 0x8100);
>> +	out_be32(&p->vtpid, ETH_P_8021Q);
>>  
>>  	/* Receive mode register */
>>  	r = emac_iff2rmr(ndev);
>> @@ -1435,6 +1436,22 @@ static inline netdev_tx_t emac_xmit_finish(struct emac_instance *dev, int len)
>>  	return NETDEV_TX_OK;
>>  }
>>  
>> +static inline u16 emac_tx_vlan(struct emac_instance *dev, struct sk_buff *skb)
>> +{
>> +	/* Handle VLAN TPID and TCI insert if this is a VLAN skb */
>> +	if (emac_has_feature(dev, EMAC_FTR_HAS_VLAN_CTAG_TX) &&
>> +	    skb_vlan_tag_present(skb)) {
>> +		struct emac_regs __iomem *p = dev->emacp;
>> +
>> +		/* update the VLAN TCI */
>> +		out_be32(&p->vtci, (u32)skb_vlan_tag_get(skb));
> 
> The only case where this is likely not going to be 0x8100/ETH_P_8021Q is
> if you do 802.1ad (QinQ) and you decided to somehow offload the S-Tag
> instead of the C-Tag.

Sorry, looks like I mixed up TCI and TPID here, this looks obviously
correct ;)
-- 
Florian