Re: [PATCH kernel v3] PCI/DOE: Support discovery version 2

[Alexey Kardashevskiy <aik@xxxxxxx>]

On 7/3/24 16:06, Kuppuswamy Sathyanarayanan wrote:
> On 3/6/24 6:20 PM, Alexey Kardashevskiy wrote:
> > PCIe r6.1, sec 6.30.1.1 defines a "DOE Discovery Version" field in
> > the DOE Discovery Request Data Object Contents (3rd DW) as:
> >
> > 15:8 DOE Discovery Version – must be 02h if the Capability Version in
> > the Data Object Exchange Extended Capability is 02h or greater.
>
> Does this change fix any functional issue? If yes, please add Fixes:
> tag and probably CC stable?

The issue is that before this patch the DOE driver was following PCIe 
r6.0 and it was not working on a device with DOE cap v2 added in r6.1. 
Is it "fixes"?


> > Add support for the version on devices with the DOE v2 capability.
> >
> > Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxx>
> > ---
> Change wise looks fine to me.
>
> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>

Thanks!

> > Changes:
> > v3:
> > * updated subject line
> > * dropped "DISCOVER_" from the new field macro
> >
> > v2:
> > * added the section number to the commit log
> > ---
> >   include/uapi/linux/pci_regs.h |  1 +
> >   drivers/pci/doe.c             | 11 ++++++++---
> >   2 files changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> > index a39193213ff2..fbca743b2b86 100644
> > --- a/include/uapi/linux/pci_regs.h
> > +++ b/include/uapi/linux/pci_regs.h
> > @@ -1144,6 +1144,7 @@
> >   #define PCI_DOE_DATA_OBJECT_HEADER_2_LENGTH		0x0003ffff
> >   
> >   #define PCI_DOE_DATA_OBJECT_DISC_REQ_3_INDEX		0x000000ff
> > +#define PCI_DOE_DATA_OBJECT_DISC_REQ_3_VER		0x0000ff00
> >   #define PCI_DOE_DATA_OBJECT_DISC_RSP_3_VID		0x0000ffff
> >   #define PCI_DOE_DATA_OBJECT_DISC_RSP_3_PROTOCOL		0x00ff0000
> >   #define PCI_DOE_DATA_OBJECT_DISC_RSP_3_NEXT_INDEX	0xff000000
> > diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
> > index 61f0531d2b1d..c94c2b0767f3 100644
> > --- a/drivers/pci/doe.c
> > +++ b/drivers/pci/doe.c
> > @@ -381,11 +381,13 @@ static void pci_doe_task_complete(struct pci_doe_task *task)
> >   	complete(task->private);
> >   }
> >   
> > -static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
> > +static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 capver, u8 *index, u16 *vid,
> >   			     u8 *protocol)
> >   {
> >   	u32 request_pl = FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_INDEX,
> > -				    *index);
> > +				    *index) |
> > +			 FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_VER,
> > +				    (capver >= 2) ? 2 : 0);
> >   	__le32 request_pl_le = cpu_to_le32(request_pl);
> >   	__le32 response_pl_le;
> >   	u32 response_pl;
> > @@ -419,13 +421,16 @@ static int pci_doe_cache_protocols(struct pci_doe_mb *doe_mb)
> >   {
> >   	u8 index = 0;
> >   	u8 xa_idx = 0;
> > +	u32 hdr = 0;
> > +
> > +	pci_read_config_dword(doe_mb->pdev, doe_mb->cap_offset, &hdr);
> >   
> >   	do {
> >   		int rc;
> >   		u16 vid;
> >   		u8 prot;
> >   
> > -		rc = pci_doe_discovery(doe_mb, &index, &vid, &prot);
> > +		rc = pci_doe_discovery(doe_mb, PCI_EXT_CAP_VER(hdr), &index, &vid, &prot);
> >   		if (rc)
> >   			return rc;
> >   

--
Alexey