[dpdk-dev] [PATCH v3] i40e: configure MTU

[Yong Wang]

On 6/16/16, 10:40 AM, "dev on behalf of Yong Wang" <dev-bounces at dpdk.org on behalf of yongwang at vmware.com> wrote:

>On 5/16/16, 5:27 AM, "dev on behalf of Olivier Matz" <dev-bounces at dpdk.org on behalf of olivier.matz at 6wind.com> wrote:
>
>>Hi Beilei,
>>
>>On 05/13/2016 10:15 AM, Beilei Xing wrote:
>>> This patch enables configuring MTU for i40e.
>>> Since changing MTU needs to reconfigure queue, stop port first
>>> before configuring MTU.
>>> 
>>> Signed-off-by: Beilei Xing <beilei.xing at intel.com>
>>> ---
>>> v3 changes:
>>>  Add frame size with extra I40E_VLAN_TAG_SIZE.
>>>  Delete i40e_dev_rx_init(pf) cause it will be called when port starts.
>>> 
>>> v2 changes:
>>>  If mtu is not within the allowed range, return -EINVAL instead of -EBUSY.
>>>  Delete rxq reconfigure cause rxq reconfigure will be finished in
>>>  i40e_dev_rx_init.
>>>    
>>>  drivers/net/i40e/i40e_ethdev.c | 34 ++++++++++++++++++++++++++++++++++
>>>  1 file changed, 34 insertions(+)
>>> 
>>> [...]
>>> +static int
>>> +i40e_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
>>> +{
>>> +	struct i40e_pf *pf = I40E_DEV_PRIVATE_TO_PF(dev->data->dev_private);
>>> +	struct rte_eth_dev_data *dev_data = pf->dev_data;
>>> +	uint32_t frame_size = mtu + ETHER_HDR_LEN
>>> +			      + ETHER_CRC_LEN + I40E_VLAN_TAG_SIZE;
>>> +	int ret = 0;
>>> +
>>> +	/* check if mtu is within the allowed range */
>>> +	if ((mtu < ETHER_MIN_MTU) || (frame_size > I40E_FRAME_SIZE_MAX))
>>> +		return -EINVAL;
>>> +
>>> +	/* mtu setting is forbidden if port is start */
>>> +	if (dev_data->dev_started) {
>>> +		PMD_DRV_LOG(ERR,
>>> +			    "port %d must be stopped before configuration\n",
>>> +			    dev_data->port_id);
>>> +		return -ENOTSUP;
>>> +	}
>>
>>I'm not convinced that ENOTSUP is the proper return value here.
>>It is usually returned when a function is not implemented, which
>>is not the case here: the function is implemented but is forbidden
>>because the port is running.
>>
>>I saw that Julien commented on your v1 that the return value should
>>be one of:
>> - (0) if successful.
>> - (-ENOTSUP) if operation is not supported.
>> - (-ENODEV) if *port_id* invalid.
>> - (-EINVAL) if *mtu* invalid.
>>
>>But I think your initial value (-EBUSY) was fine. Maybe it should be
>>added in the API instead, with the following description:
>>  (-EBUSY) if the operation is not allowed when the port is running
>
>AFAICT, the same check is not done for other drivers that implement
>the mac_set op. Wouldn’t it make more sense to have the driver disable

Correction: this should read as mtu_set.

>the port, reconfigure and re-enable it in this case, instead of returning
>error code?  If the consensus in DPDK is to have the application disable
>the port first, we need to enforce this policy across all devices and
>clearly document this behavior.
>
>>This would allow the application to take its dispositions to stop the
>>port and restart it with the proper jumbo_frame argument.
>>
>>+CC Thomas which maintains ethdev API.
>>
>>
>>Regards,
>>Olivier
>