[PATCH] PCI/DPC: Check host->native_dpc before enable dpc service

[PATCH] PCI/DPC: Check host->native_dpc before enable dpc service

[Yicong Yang]

Per PCI Firmware Specification Rev. 3.2 Table 4-6,
Interpretation of _OSC Control Field Returned Value, for
bit 7 of _OSC control return value:

  "Firmware sets this bit to 1 to grant the OS control over PCI Express
  Downstream Port Containment configuration."
  "If control of this feature was requested and denied,
  or was not requested, the firmware returns this bit set to 0."

We store bit 7 of _OSC control return value in host->native_dpc,
check it before enable the dpc service as the firmware may not
grant the control.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/pci/pcie/portdrv_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
index e1fed664..7445d03 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c
@@ -253,7 +253,8 @@ static int get_port_device_capability(struct pci_dev *dev)
 	 */
 	if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) &&
 	    pci_aer_available() &&
-	    (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER)))
+	    (pcie_ports_dpc_native ||
+	    ((services & PCIE_PORT_SERVICE_AER) && host->native_dpc)))
 		services |= PCIE_PORT_SERVICE_DPC;
 
 	if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM ||
-- 
2.8.1

Re: [PATCH] PCI/DPC: Check host->native_dpc before enable dpc service

[Yicong Yang]

On 2021/2/3 20:13, Yicong Yang wrote:
> Per PCI Firmware Specification Rev. 3.2 Table 4-6,
> Interpretation of _OSC Control Field Returned Value, for
> bit 7 of _OSC control return value:

Downstream Port Containment Related Enhancements ECN, Jan 28, 2019,
affecting PCI Firmware Specification, Rev. 3.2.

will resend to fix this. sorry.