netdev - Re: [PATCH net-next v1] idpf: add support for IDPF PCI programming interface

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Message-ID: <1ced3c08-5b96-431d-8542-7e7b746156d3@intel.com>
Date: Thu, 28 Aug 2025 13:27:01 -0700
From: "Chittim, Madhu" <madhu.chittim@...el.com>
To: Simon Horman <horms@...nel.org>, "Linga, Pavan Kumar"
	<Pavan.Kumar.Linga@...el.com>
CC: "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>, "Samudrala, Sridhar"
	<sridhar.samudrala@...el.com>
Subject: Re: [PATCH net-next v1] idpf: add support for IDPF PCI programming
 interface



On 8/28/2025 3:40 AM, Simon Horman wrote:
> On Tue, Aug 26, 2025 at 10:28:45AM -0700, Pavan Kumar Linga wrote:
>> At present IDPF supports only 0x1452 and 0x145C as PF and VF device IDs
>> on our current generation hardware. Future hardware exposes a new set of
>> device IDs for each generation. To avoid adding a new device ID for each
>> generation and to make the driver forward and backward compatible,
>> make use of the IDPF PCI programming interface to load the driver.
>>
>> Write and read the VF_ARQBAL mailbox register to find if the current
>> device is a PF or a VF.
>>
>> PCI SIG allocated a new programming interface for the IDPF compliant
>> ethernet network controller devices. It can be found at:
>> https://members.pcisig.com/wg/PCI-SIG/document/20113
>> with the document titled as 'PCI Code and ID Assignment Revision 1.16'
>> or any latest revisions.
>>
>> Reviewed-by: Madhu Chittim <madhu.chittim@...el.com>
>> Reviewed-by: Sridhar Samudrala <sridhar.samudrala@...el.com>
>> Signed-off-by: Pavan Kumar Linga <pavan.kumar.linga@...el.com>
> 
> ...
> 
>> diff --git a/drivers/net/ethernet/intel/idpf/idpf_main.c b/drivers/net/ethernet/intel/idpf/idpf_main.c
>> index 8c46481d2e1f..b161715e1168 100644
>> --- a/drivers/net/ethernet/intel/idpf/idpf_main.c
>> +++ b/drivers/net/ethernet/intel/idpf/idpf_main.c
>> @@ -7,11 +7,57 @@
>>   
>>   #define DRV_SUMMARY	"Intel(R) Infrastructure Data Path Function Linux Driver"
>>   
>> +#define IDPF_NETWORK_ETHERNET_PROGIF				0x01
>> +#define IDPF_CLASS_NETWORK_ETHERNET_PROGIF			\
>> +	(PCI_CLASS_NETWORK_ETHERNET << 8 | IDPF_NETWORK_ETHERNET_PROGIF)
>> +
>>   MODULE_DESCRIPTION(DRV_SUMMARY);
>>   MODULE_IMPORT_NS("LIBETH");
>>   MODULE_IMPORT_NS("LIBETH_XDP");
>>   MODULE_LICENSE("GPL");
>>   
>> +/**
>> + * idpf_dev_init - Initialize device specific parameters
>> + * @adapter: adapter to initialize
>> + * @ent: entry in idpf_pci_tbl
>> + *
>> + * Return: %0 on success, -%errno on failure.
>> + */
>> +static int idpf_dev_init(struct idpf_adapter *adapter,
>> +			 const struct pci_device_id *ent)
>> +{
>> +	u8 is_vf = 0;
>> +	int err;
>> +
>> +	switch (ent->device) {
>> +	case IDPF_DEV_ID_PF:
>> +		goto dev_ops_init;
>> +	case IDPF_DEV_ID_VF:
>> +		is_vf = 1;
>> +		goto dev_ops_init;
>> +	default:
>> +		if (ent->class == IDPF_CLASS_NETWORK_ETHERNET_PROGIF)
>> +			goto check_vf;
>> +
>> +		return -ENODEV;
>> +	}
>> +
>> +check_vf:
>> +	err = idpf_is_vf_device(adapter->pdev, &is_vf);
>> +	if (err)
>> +		return err;
>> +
>> +dev_ops_init:
>> +	if (is_vf) {
>> +		idpf_vf_dev_ops_init(adapter);
>> +		adapter->crc_enable = true;
>> +	} else {
>> +		idpf_dev_ops_init(adapter);
>> +	}
>> +
>> +	return 0;
>> +}
> 
> Hi Pavan,
> 
> I think that in Kernel Networking code the usual use cases
> of goto labels are: for error handling; and, optimisation,
> f.e. in the datapath.
> 
> I don't think this code falls into either category.
> So I suggest implementing it without gotos.
> 
> Thanks!
> 
Pavan is on Vacation, will fix it in v3. Thank you> ...