On 2/16/24 11:01 AM, Bean Huo wrote:
From: Bean Huo beanhuo@micron.com
The PCIe specification allows up to 8 Physical Functions (PFs) per endpoint when ARI (Alternative Routing-ID Interpretation) is not supported. Previously, our implementation erroneously limited the maximum number of PFs to 7 for endpoints without ARI support.
I would quote specification reference here, like below:
As per PCIe specification r6.2, sec titled "Alternative Routing-ID Interpretation (ARI)", up to 8 [fn # 0..7] functions are allowed in an non ARI capable device.
It looks like for an ARI capable device the limit is 256. Why not add that check as well?
This patch corrects the maximum PF count to adhere to the PCIe specification by allowing up to 8 PFs on non-ARI endpoints. This change ensures better compliance with the standard and improves compatibility with devices relying on this specification.
The necessity for this adjustment was verified by a thorough review of the "Alternative Routing-ID Interpretation (ARI)" section in the PCIe 3.0 Spec, which first introduced ARI.
I would always use latest PCIe spec for reference.
Fixes: c3df83e01a96 ("PCI: Clean up pci_scan_slot()") Cc: stable@vger.kernel.org Signed-off-by: Bean Huo beanhuo@micron.com
Changelog: v1--v2: 1. Add Fixes tag 2. Modify commit message
drivers/pci/probe.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index ed6b7f48736a..8c3d0f63bc13 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2630,7 +2630,8 @@ static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn) if (pci_ari_enabled(bus)) return next_ari_fn(bus, dev, fn);
- if (fn >= 7)
- /* If EP does not support ARI, the maximum number of functions should be 7 */
- if (fn > 7) return -ENODEV; /* only multifunction devices may have more functions */ if (dev && !dev->multifunction)