[PATCH v8 3/7] PCI/TPH: Fix pcie_tph_get_st_table_size() for MSI-X table location

[Chengwen Feng <fengchengwen@huawei.com>]

pcie_tph_get_st_table_size() previously only returned valid size when ST
Table is in TPH Capability space. According to PCIe spec [1], ST table size
is also valid when ST Table is located in MSI-X table.

Fix it to return valid table size for both PCI_TPH_LOC_CAP and
PCI_TPH_LOC_MSIX locations.

[1] PCI Express Base 6.1 Table 7-258 TPH Requester Capability Register
ST Table Size:
- Value indicates the maximum number of ST Table entries the Function may
  use. Software reads this field to determine the ST Table Size N, which is
  encoded as N-1. For example, a returned value of 000 0000 0011b indicates
  a table size of four entries.
- There is an upper limit of 64 entries when the ST Table is located in the
  TPH Requester Extended Capability structure.
- When the ST Table is located in the MSI-X Table, this value is limited by
  the size of the MSI-X Table.
- This field is only applicable for Functions that implement an ST Table as
  indicated by the ST Table Location field. Otherwise, the value in this
  field is undefined.

Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
---
 drivers/pci/tph.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c
index ba31b010f67a..de5bd7039cdc 100644
--- a/drivers/pci/tph.c
+++ b/drivers/pci/tph.c
@@ -191,7 +191,8 @@ EXPORT_SYMBOL(pcie_tph_get_st_table_loc);
 
 /*
  * Return the size of ST table. If ST table is not in TPH Requester Extended
- * Capability space, return 0. Otherwise return the ST Table Size + 1.
+ * Capability space or MSI-X table, return 0. Otherwise return the
+ * ST Table Size + 1.
  */
 u16 pcie_tph_get_st_table_size(struct pci_dev *pdev)
 {
@@ -200,7 +201,7 @@ u16 pcie_tph_get_st_table_size(struct pci_dev *pdev)
 
 	/* Check ST table location first */
 	loc = pcie_tph_get_st_table_loc(pdev);
-	if (loc != PCI_TPH_LOC_CAP)
+	if (loc != PCI_TPH_LOC_CAP && loc != PCI_TPH_LOC_MSIX)
 		return 0;
 
 	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, &reg);
-- 
2.17.1