[PATCH] pci: Don't set RCB bit in LNKCTL if the upstream bridge hasn't

[Johannes Thumshirn]

The Read Completion Boundary bit must only be set on a device or endpoint if
it is set on the upstream bridge.

Fixes: 7a1562d4f ("PCI: Apply _HPX Link Control settings to all devices with a 
link")
Signed-off-by: Johannes Thumshirn <jthumsh...@suse.de>
---
 drivers/pci/probe.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index ab00267..5007b96 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1439,6 +1439,16 @@ static void program_hpp_type1(struct pci_dev *dev, 
struct hpp_type1 *hpp)
                dev_warn(&dev->dev, "PCI-X settings not supported\n");
 }
 
+static bool pcie_get_upstream_rcb(struct pci_dev *dev)
+{
+       struct pci_dev *bridge = pci_upstream_bridge(dev);
+       u16 lnkctl;
+
+       pcie_capability_read_word(bridge, PCI_EXP_LNKCTL, &lnkctl);
+
+       return lnkctl & PCI_EXP_LNKCTL_RCB;
+}
+
 static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp)
 {
        int pos;
@@ -1468,9 +1478,21 @@ static void program_hpp_type2(struct pci_dev *dev, 
struct hpp_type2 *hpp)
                        ~hpp->pci_exp_devctl_and, hpp->pci_exp_devctl_or);
 
        /* Initialize Link Control Register */
-       if (pcie_cap_has_lnkctl(dev))
+       if (pcie_cap_has_lnkctl(dev)) {
+               bool us_rcb;
+               u16 clear;
+               u16 set;
+
+               us_rcb = pcie_get_upstream_rcb(dev);
+
+               clear = ~hpp->pci_exp_lnkctl_and;
+               set = hpp->pci_exp_lnkctl_or;
+               if (!us_rcb)
+                       set &= ~PCI_EXP_LNKCTL_RCB;
+
                pcie_capability_clear_and_set_word(dev, PCI_EXP_LNKCTL,
-                       ~hpp->pci_exp_lnkctl_and, hpp->pci_exp_lnkctl_or);
+                                                 clear, set);
+       }
 
        /* Find Advanced Error Reporting Enhanced Capability */
        pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
-- 
1.8.5.6