linux-kernel - Re: [PATCH kernel v2] pci/doe: Support discovery version

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Date: Tue, 27 Feb 2024 21:41:16 +0100
From: Lukas Wunner <lukas@...ner.de>
To: Alexey Kardashevskiy <aik@....com>
Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Ira Weiny <ira.weiny@...el.com>
Subject: Re: [PATCH kernel v2] pci/doe: Support discovery version

On Mon, Feb 26, 2024 at 02:31:14PM +1100, Alexey Kardashevskiy wrote:
> Does PCI_DOE_DATA_OBJECT_DISC_REQ_3_DISCOVER_VER need to be in pci-regs.h?

Yes that's fine.


> --- 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_DISCOVER_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

"DISCOVER" duplicates the preceding "DISC", maybe just
"PCI_DOE_DATA_OBJECT_DISC_REQ_3_VERSION" for simplicity?


> -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 disver = FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_DISCOVER_VER,
> +				(capver >= 2) ? 2 : 0);
>  	u32 request_pl = FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_INDEX,
> -				    *index);
> +				    *index) | disver;

Hm, why use a separate "disver" variable?  This could be combined
into a single statement.

Subject should probably be "PCI/DOE: Support discovery version 2".

Otherwise LGTM.

Thanks,

Lukas