PCI: aardvark: Refactor unmasking summary MSI interrupt

Refactor the masking of ISR0/1 Sources and unmasking of summary MSI interrupt
so that it corresponds to the comments:
- first mask all ISR0/1
- then unmask all MSIs
- then unmask summary MSI interrupt

Link: https://lore.kernel.org/r/20220110015018.26359-10-kabel@kernel.org
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/controller/pci-aardvark.c

@@ -571,15 +571,17 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie)
 	advk_writel(pcie, PCIE_IRQ_ALL_MASK, HOST_CTRL_INT_STATUS_REG);
 
 	/* Disable All ISR0/1 Sources */
-	reg = PCIE_ISR0_ALL_MASK;
-	reg &= ~PCIE_ISR0_MSI_INT_PENDING;
-	advk_writel(pcie, reg, PCIE_ISR0_MASK_REG);
-
+	advk_writel(pcie, PCIE_ISR0_ALL_MASK, PCIE_ISR0_MASK_REG);
 	advk_writel(pcie, PCIE_ISR1_ALL_MASK, PCIE_ISR1_MASK_REG);
 
 	/* Unmask all MSIs */
 	advk_writel(pcie, ~(u32)PCIE_MSI_ALL_MASK, PCIE_MSI_MASK_REG);
 
+	/* Unmask summary MSI interrupt */
+	reg = advk_readl(pcie, PCIE_ISR0_MASK_REG);
+	reg &= ~PCIE_ISR0_MSI_INT_PENDING;
+	advk_writel(pcie, reg, PCIE_ISR0_MASK_REG);
+
 	/* Enable summary interrupt for GIC SPI source */
 	reg = PCIE_IRQ_ALL_MASK & (~PCIE_IRQ_ENABLE_INTS_MASK);
 	advk_writel(pcie, reg, HOST_CTRL_INT_MASK_REG);