Re: [PATCH v1 7/7] fpga: dfl: pci: Add generic OFS PCI PID

[matthew.gerlach@linux.intel.com]

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On Fri, 18 Feb 2022, Tom Rix wrote:

>
> On 2/18/22 1:03 AM, Zhang, Tianfei wrote:
>> 
>>> -----Original Message-----
>>> From: Tom Rix <trix@redhat.com>
>>> Sent: Wednesday, February 16, 2022 12:16 AM
>>> To: Zhang, Tianfei <tianfei.zhang@intel.com>; Wu, Hao <hao.wu@intel.com>;
>>> mdf@kernel.org; Xu, Yilun <yilun.xu@intel.com>; 
>>> linux-fpga@vger.kernel.org;
>>> linux-doc@vger.kernel.org; linux-kernel@vger.kernel.org
>>> Cc: corbet@lwn.net; Matthew Gerlach <matthew.gerlach@linux.intel.com>
>>> Subject: Re: [PATCH v1 7/7] fpga: dfl: pci: Add generic OFS PCI PID
>>> 
>>> 
>>> On 2/14/22 3:26 AM, Tianfei zhang wrote:
>>>> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>>>> 
>>>> Add the PCI product id for an Open FPGA Stack PCI card.
>>> Is there a URL to the card ?
>> This PCIe Device IDs have registered by Intel.
> A URL is useful to introduce the board, Is there one ?
>> 
>>>> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>>>> Signed-off-by: Tianfei Zhang <tianfei.zhang@intel.com>
>>>> ---
>>>>    drivers/fpga/dfl-pci.c | 4 ++++
>>>>    1 file changed, 4 insertions(+)
>>>> 
>>>> diff --git a/drivers/fpga/dfl-pci.c b/drivers/fpga/dfl-pci.c index
>>>> 83b604d6dbe6..cb2fbf3eb918 100644
>>>> --- a/drivers/fpga/dfl-pci.c
>>>> +++ b/drivers/fpga/dfl-pci.c
>>>> @@ -76,12 +76,14 @@ static void cci_pci_free_irq(struct pci_dev *pcidev)
>>>>    #define PCIE_DEVICE_ID_INTEL_PAC_D5005		0x0B2B
>>>>    #define PCIE_DEVICE_ID_SILICOM_PAC_N5010	0x1000
>>>>    #define PCIE_DEVICE_ID_SILICOM_PAC_N5011	0x1001
>>>> +#define PCIE_DEVICE_ID_INTEL_OFS		0xbcce
>>> INTEL_OFS is a generic name, pci id's map to specific cards
>>> 
>>> Is there a more specific name for this card ?
>> I think using INTEL_OFS is better, because INTEL_OFS is the Generic 
>> development platform can support multiple cards which using OFS 
>> specification,
>> like Intel PAC N6000 card.
>
> I would prefer something like PCIE_DEVICE_ID_INTEL_PAC_N6000 because it 
> follows an existing pattern.  Make it easy on a developer, they will look at 
> their board or box, see X and try to find something similar in the driver 
> source.
>
> To use OSF_ * the name needs a suffix to differentiate it from future cards 
> that will also use ofs.
>
> If this really is a generic id please explain in the doc patch how every 
> future board with use this single id and how a driver could work around a hw 
> problem in a specific board with a pci id covering multiple boards.
>
> Tom

Hi Tom,

The intent is to have a generic device id that can be used with many 
different boards.  Currently, we have FPGA implementations for 3 different 
boards using this generic id.  We may need a better name for device id 
than OFS.  More precisely this generic device id means a PCI function that 
is described by a Device Feature List (DFL).  How about 
PCIE_DEVICE_ID_INTEL_DFL?

With a DFL device id, the functionality of the PF/VF is determined by the 
contents of the DFL.  Each Device Feature Header (DFH) in the DFL has a 
revision field that can be used identify "broken" hw, or new functionality 
added to a feature.  Additionally, since the DFL is typically used in a 
FPGA, the broken hardware, can and should be fixed in most cases.

Matthew
>
>> 
>>> Tom
>>>
>>>>    /* VF Device */
>>>>    #define PCIE_DEVICE_ID_VF_INT_5_X		0xBCBF
>>>>    #define PCIE_DEVICE_ID_VF_INT_6_X		0xBCC1
>>>>    #define PCIE_DEVICE_ID_VF_DSC_1_X		0x09C5
>>>>    #define PCIE_DEVICE_ID_INTEL_PAC_D5005_VF	0x0B2C
>>>> +#define PCIE_DEVICE_ID_INTEL_OFS_VF		0xbccf
>>>>
>>>>    static struct pci_device_id cci_pcie_id_tbl[] = {
>>>>    	{PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCIE_DEVICE_ID_PF_INT_5_X),},
>>> @@
>>>> -95,6 +97,8 @@ static struct pci_device_id cci_pcie_id_tbl[] = {
>>>>    	{PCI_DEVICE(PCI_VENDOR_ID_INTEL,
>>> PCIE_DEVICE_ID_INTEL_PAC_D5005_VF),},
>>>>    	{PCI_DEVICE(PCI_VENDOR_ID_SILICOM_DENMARK,
>>> PCIE_DEVICE_ID_SILICOM_PAC_N5010),},
>>>>    	{PCI_DEVICE(PCI_VENDOR_ID_SILICOM_DENMARK,
>>>> PCIE_DEVICE_ID_SILICOM_PAC_N5011),},
>>>> +	{PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCIE_DEVICE_ID_INTEL_OFS),},
>>>> +	{PCI_DEVICE(PCI_VENDOR_ID_INTEL,
>>> PCIE_DEVICE_ID_INTEL_OFS_VF),},
>>>>    	{0,}
>>>>    };
>>>>    MODULE_DEVICE_TABLE(pci, cci_pcie_id_tbl);
>
>