[PATCH net v2] octeontx2-af: Fix limiting SRIOV VF count logic

[nshettyj]

From: Sunil Goutham <sgoutham@xxxxxxxxxxx>

When RVU PF0/AF's VFs are SDP instead of LBK, limiting the VF count
based on the LBK channel count is incorrect.

Apply LBK channel-based VF limits only when the VF device ID matches
the LBK RVU AFVF device.

Fixes: 9bd6caf33567 ("octeontx2-af: Enable sriov on AF to create VFs")
Signed-off-by: Sunil Goutham <sgoutham@xxxxxxxxxxx>
Signed-off-by: Nitin Shetty J <nshettyj@xxxxxxxxxxx>
---
v2:
 - Use min() to simplify VF count capping
 - guard against negative vfs when chans < 2
---
 .../net/ethernet/marvell/octeontx2/af/rvu.c   | 33 +++++++++++--------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
index 74c041ab5280..937b085582b5 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
@@ -3468,6 +3468,8 @@ int rvu_get_num_lbk_chans(void)
 	return ret;
 }
 
+#define PCI_DEVID_OCTEONTX2_RVU_AFVF	0xA0F8
+
 static int rvu_enable_sriov(struct rvu *rvu)
 {
 	struct pci_dev *pdev = rvu->pdev;
@@ -3486,24 +3488,27 @@ static int rvu_enable_sriov(struct rvu *rvu)
 		return 0;
 	pci_read_config_word(pdev, pos + PCI_SRIOV_VF_DID, &rvu->vf_devid);
 
-	chans = rvu_get_num_lbk_chans();
-	if (chans < 0)
-		return chans;
-
 	vfs = pci_sriov_get_totalvfs(pdev);
-
-	/* Limit VFs in case we have more VFs than LBK channels available. */
-	if (vfs > chans)
-		vfs = chans;
-
 	if (!vfs)
 		return 0;
 
-	/* LBK channel number 63 is used for switching packets between
-	 * CGX mapped VFs. Hence limit LBK pairs till 62 only.
-	 */
-	if (vfs > 62)
-		vfs = 62;
+	if (rvu->vf_devid == PCI_DEVID_OCTEONTX2_RVU_AFVF) {
+		chans = rvu_get_num_lbk_chans();
+		if (chans < 0)
+			return chans;
+
+		/* The last LBK channel is reserved for switching packets between
+		 * CGX mapped VFs. Also, since LBK VFs work in pairs, limit VF
+		 * count to available LBK channels minus 2.
+		 */
+		vfs = min(vfs, chans - 2);
+
+		if (vfs <= 0) {
+			dev_warn(&pdev->dev,
+				 "Skipping SRIOV enablement, not enough LBK channels available\n");
+			return 0;
+		}
+	}
 
 	/* Save VFs number for reference in VF interrupts handlers.
 	 * Since interrupts might start arriving during SRIOV enablement
-- 
2.48.1