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

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Message-ID: <32ac2ee6-26b1-4f37-bd88-db1ef2a31267@linux.intel.com>
Date: Wed, 6 Mar 2024 21:06:20 -0800
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Alexey Kardashevskiy <aik@....com>, linux-pci@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
 Ira Weiny <ira.weiny@...el.com>, Dan Williams <dan.j.williams@...el.com>,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 Lukas Wunner <lukas@...ner.de>
Subject: Re: [PATCH kernel v3] PCI/DOE: Support discovery version 2


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?

>
> Add support for the version on devices with the DOE v2 capability.
>
> Signed-off-by: Alexey Kardashevskiy <aik@....com>
> ---
Change wise looks fine to me.

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> 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;
>  

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer