[PATCH V2] PCI/TPH: Skip Root Port completer check for RC_END devices

[George Abraham P <george.abraham.p@intel.com>]

Root Complex Integrated Endpoint devices (PCI_EXP_TYPE_RC_END) are
directly integrated into the root complex and do not have an
associated Root Port in the traditional PCIe hierarchy. The current
TPH implementation incorrectly attempts to find and check a Root Port's
TPH completer capability for these devices.

Add a check to skip Root Port completer type verification for RC_END
devices, allowing them to use their full TPH requester capability
without being limited by a non-existent Root Port's completer support.

For RC_END devices, the root complex itself acts as the TPH completer,
and this relationship is handled differently than the standard
endpoint-to-Root-Port model.

Fixes: f69767a1ada3 ("PCI: Add TLP Processing Hints (TPH) support")
Signed-off-by: George Abraham P <george.abraham.p@intel.com>
---
v1->v2:
  - Added "Fixes:" tag to link the commit hash that introduced the code

 drivers/pci/tph.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c
index cc64f93709a4..c61456d24f61 100644
--- a/drivers/pci/tph.c
+++ b/drivers/pci/tph.c
@@ -397,10 +397,13 @@ int pcie_enable_tph(struct pci_dev *pdev, int mode)
 	else
 		pdev->tph_req_type = PCI_TPH_REQ_TPH_ONLY;
 
-	rp_req_type = get_rp_completer_type(pdev);
+	/* Check if the device is behind a Root Port */
+	if (pci_pcie_type(pdev) != PCI_EXP_TYPE_RC_END) {
+		rp_req_type = get_rp_completer_type(pdev);
 
-	/* Final req_type is the smallest value of two */
-	pdev->tph_req_type = min(pdev->tph_req_type, rp_req_type);
+		/* Final req_type is the smallest value of two */
+		pdev->tph_req_type = min(pdev->tph_req_type, rp_req_type);
+	}
 
 	if (pdev->tph_req_type == PCI_TPH_REQ_DISABLE)
 		return -EINVAL;

base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
-- 
2.40.1