From: Pali Rohár pali@kernel.org
commit 754e449889b22fc3c34235e8836f08f51121d307 upstream.
According to PCI 3.0 specification, sending both MSI and MSI-X interrupts is done by DWORD memory write operation to doorbell message address. The write operation for MSI has zero upper 16 bits and the MSI interrupt number in the lower 16 bits, while the write operation for MSI-X contains a 32-bit value from MSI-X table.
Since the driver only uses interrupt numbers from range 0..31, the upper 16 bits of the DWORD memory write operation to doorbell message address are zero even for MSI-X interrupts. Thus we can enable MSI-X interrupts.
Testing proves that kernel can correctly receive MSI-X interrupts from PCIe cards which supports both MSI and MSI-X interrupts.
Link: https://lore.kernel.org/r/20220110015018.26359-13-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 Signed-off-by: Marek Behún kabel@kernel.org --- drivers/pci/controller/pci-aardvark.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c index 43f79cbf9027..4cc88fa66979 100644 --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -1339,7 +1339,7 @@ static struct irq_chip advk_msi_irq_chip = {
static struct msi_domain_info advk_msi_domain_info = { .flags = MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS | - MSI_FLAG_MULTI_PCI_MSI, + MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX, .chip = &advk_msi_irq_chip, };