[PATCH 4.19 236/313] PCI: imx: Enable MSI from downstream components

From: Greg Kroah-Hartman
Date: Mon Feb 11 2019 - 10:38:50 EST

4.19-stable review patch. If anyone has any objections, please let me know.


[ Upstream commit 75cb8d20c112aba70f23d98e3f8d0a38ace16006 ]

The MSI Enable bit in the MSI Capability (PCIe r4.0, sec controls
whether a Function can request service using MSI.

i.MX6 Root Ports implement the MSI Capability and may use MSI to request
service for events like PME, hotplug, AER, etc. In addition, on i.MX6, the
MSI Enable bit controls delivery of MSI interrupts from components below
the Root Port.

Prior to f3fdfc4ac3a2 ("PCI: Remove host driver Kconfig selection of
CONFIG_PCIEPORTBUS"), enabling CONFIG_PCI_IMX6 automatically also enabled
CONFIG_PCIEPORTBUS, and when portdrv claimed the Root Ports, it set the MSI
Enable bit so it could use PME, hotplug, AER, etc. As a side effect, that
also enabled delivery of MSI interrupts from downstream components.

The imx6q-pcie driver itself does not depend on portdrv, so set MSI Enable
in imx6q-pcie so MSI from downstream components works even if nobody uses
MSI for the Root Port events.

Fixes: f3fdfc4ac3a2 ("PCI: Remove host driver Kconfig selection of CONFIG_PCIEPORTBUS")
Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Tested-by: Sven Van Asbroeck <TheSven73@xxxxxxxxxxxxxx>
Tested-by: Trent Piepho <tpiepho@xxxxxxxxxx>
Reviewed-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/pci/controller/dwc/pci-imx6.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 975050a69494..3826b444298c 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -66,6 +66,7 @@ struct imx6_pcie {

/* PCIe Root Complex registers (memory-mapped) */
+#define PCIE_RC_IMX6_MSI_CAP 0x50
#define PCIE_RC_LCR 0x7c
@@ -682,6 +683,7 @@ static int imx6_pcie_probe(struct platform_device *pdev)
struct resource *dbi_base;
struct device_node *node = dev->of_node;
int ret;
+ u16 val;

imx6_pcie = devm_kzalloc(dev, sizeof(*imx6_pcie), GFP_KERNEL);
if (!imx6_pcie)
@@ -816,6 +818,14 @@ static int imx6_pcie_probe(struct platform_device *pdev)
if (ret < 0)
return ret;

+ if (pci_msi_enabled()) {
+ val = dw_pcie_readw_dbi(pci, PCIE_RC_IMX6_MSI_CAP +
+ dw_pcie_writew_dbi(pci, PCIE_RC_IMX6_MSI_CAP + PCI_MSI_FLAGS,
+ val);
+ }
return 0;