PCI: dwc: Use interrupt masking instead of disabling

The dwc driver is showing an interesting level of brokeness, as it
insists on using the enable/disable set of registers to mask/unmask
MSIs, meaning that an MSIs being generated while the interrupt is in
that "disabled" state will simply be lost.

Let's move to the mask/unmask set of registers, which offers the
expected semantics.

Fixes: 7c5925afbc58 ("PCI: dwc: Move MSI IRQs allocation to IRQ domains
hierarchical API")
Link: https://lore.kernel.org/linux-pci/20181113225734.8026-1-marc.zyngier@arm.com/
Tested-by: Niklas Cassel <niklas.cassel@linaro.org>
Tested-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Tested-by: Stanimir Varbanov <svarbanov@mm-sol.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: stable@vger.kernel.org

1 files changed, 12 insertions, 7 deletions

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 29a05759a294..0f81b7169147 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -168,8 +168,8 @@ static void dw_pci_bottom_mask(struct irq_data *data)
                 bit = data->hwirq % MAX_MSI_IRQS_PER_CTRL;
 
                 pp->irq_status[ctrl] &= ~(1 << bit);
-                dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4,
-                                    pp->irq_status[ctrl]);
+                dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_MASK + res, 4,
+                                    ~pp->irq_status[ctrl]);
         }
 
         raw_spin_unlock_irqrestore(&pp->lock, flags);
@@ -191,8 +191,8 @@ static void dw_pci_bottom_unmask(struct irq_data *data)
                 bit = data->hwirq % MAX_MSI_IRQS_PER_CTRL;
 
                 pp->irq_status[ctrl] |= 1 << bit;
-                dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4,
-                                    pp->irq_status[ctrl]);
+                dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_MASK + res, 4,
+                                    ~pp->irq_status[ctrl]);
         }
 
         raw_spin_unlock_irqrestore(&pp->lock, flags);
@@ -658,10 +658,15 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
         num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
 
         /* Initialize IRQ Status array */
-        for (ctrl = 0; ctrl < num_ctrls; ctrl++)
-                dw_pcie_rd_own_conf(pp, PCIE_MSI_INTR0_ENABLE +
+        for (ctrl = 0; ctrl < num_ctrls; ctrl++) {
+                dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_MASK +
                                         (ctrl * MSI_REG_CTRL_BLOCK_SIZE),
-                                    4, &pp->irq_status[ctrl]);
+                                    4, ~0);
+                dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE +
+                                        (ctrl * MSI_REG_CTRL_BLOCK_SIZE),
+                                    4, ~0);
+                pp->irq_status[ctrl] = 0;
+        }
 
         /* Setup RC BARs */
         dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, 0x00000004);