Re: [PATCH 1/1] PCI/IDE: Fix using wrong VF ID for RID range calculation

[Xu Yilun <yilun.xu@linux.intel.com>]

On Sun, Jan 11, 2026 at 04:06:31PM +0800, Li Ming wrote:
> When allocate a new IDE stream for a pci device in SR-IOV case, the RID
> range of the new IDE stream should cover all VFs of the device. VF id
> range of a pci device is [0 - (num_VFs - 1)], so should use (num_VFs - )
> as the last VF's ID.
> 
> Fixes: 1e4d2ff3ae45 ("PCI/IDE: Add IDE establishment helpers")
> Signed-off-by: Li Ming <ming.li@zohomail.com>
> ---
>  drivers/pci/ide.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/ide.c b/drivers/pci/ide.c
> index 26f7cc94ec31..9629f3ceb213 100644
> --- a/drivers/pci/ide.c
> +++ b/drivers/pci/ide.c
> @@ -283,8 +283,8 @@ struct pci_ide *pci_ide_stream_alloc(struct pci_dev *pdev)
>  	/* for SR-IOV case, cover all VFs */
>  	num_vf = pci_num_vf(pdev);
>  	if (num_vf)
> -		rid_end = PCI_DEVID(pci_iov_virtfn_bus(pdev, num_vf),
> -				    pci_iov_virtfn_devfn(pdev, num_vf));
> +		rid_end = PCI_DEVID(pci_iov_virtfn_bus(pdev, num_vf - 1),
> +				    pci_iov_virtfn_devfn(pdev, num_vf - 1));

I don't have VF for test but I believe the change is correct.

The calculated rid_end will be passed to IDE RID association register values,
which is inclusive according to IDE SPEC.

  void pci_ide_stream_to_regs(...)
  {
	...
	regs->rid1 = FIELD_PREP(PCI_IDE_SEL_RID_1_LIMIT, settings->rid_end);
	...
  }

Is it better we clarify the kernel-doc a little bit:

--------8<--------

diff --git a/include/linux/pci-ide.h b/include/linux/pci-ide.h
index 2521a2914294..f0c6975fd429 100644
--- a/include/linux/pci-ide.h
+++ b/include/linux/pci-ide.h
@@ -26,7 +26,7 @@ enum pci_ide_partner_select {
 /**
  * struct pci_ide_partner - Per port pair Selective IDE Stream settings
  * @rid_start: Partner Port Requester ID range start
- * @rid_end: Partner Port Requester ID range end
+ * @rid_end: Partner Port Requester ID range end (inclusive)
  * @stream_index: Selective IDE Stream Register Block selection
  * @mem_assoc: PCI bus memory address association for targeting peer partner
  * @pref_assoc: PCI bus prefetchable memory address association for