[PATCH v2 4/6] Revert "PCI: qcom: Enable MSI interrupts together with Link up if 'Global IRQ' is supported"

[Niklas Cassel <cassel@kernel.org>]

This reverts commit ba4a2e2317b9faeca9193ed6d3193ddc3cf2aba3.

While this fake hotplugging was a nice idea, it has shown that this feature
does not handle PCIe switches correctly:
pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46

During the initial scan, PCI core doesn't see the switch and since the Root
Port is not hot plug capable, the secondary bus number gets assigned as the
subordinate bus number. This means, the PCI core assumes that only one bus
will appear behind the Root Port since the Root Port is not hot plug
capable.

This works perfectly fine for PCIe endpoints connected to the Root Port,
since they don't extend the bus. However, if a PCIe switch is connected,
then there is a problem when the downstream busses starts showing up and
the PCI core doesn't extend the subordinate bus number after initial scan
during boot.

The long term plan is to migrate this driver to the pwrctrl framework,
once it adds proper support for powering up and enumerating PCIe switches.

Cc: stable@vger.kernel.org
Suggested-by: Manivannan Sadhasivam <mani@kernel.org>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index e87ec6779d44..c5fcb87972e9 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -136,7 +136,6 @@
 
 /* PARF_INT_ALL_{STATUS/CLEAR/MASK} register fields */
 #define PARF_INT_ALL_LINK_UP			BIT(13)
-#define PARF_INT_MSI_DEV_0_7			GENMASK(30, 23)
 
 /* PARF_NO_SNOOP_OVERRIDE register fields */
 #define WR_NO_SNOOP_OVERRIDE_EN			BIT(1)
@@ -1982,8 +1981,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 			goto err_host_deinit;
 		}
 
-		writel_relaxed(PARF_INT_ALL_LINK_UP | PARF_INT_MSI_DEV_0_7,
-			       pcie->parf + PARF_INT_ALL_MASK);
+		writel_relaxed(PARF_INT_ALL_LINK_UP, pcie->parf + PARF_INT_ALL_MASK);
 	}
 
 	qcom_pcie_icc_opp_update(pcie);
-- 
2.52.0