On Tue, Oct 12, 2021 at 06:41:41PM +0200, Marek Behún wrote: > From: Pali Rohár <pali@xxxxxxxxxx> > > 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. It is the controller driver that defines the MSI-X data field yes, what I don't get is why we have to add this comment in the commit log. Basically Aardvark can support MSI-X up to 32 MSI-X vectors and you are enabling them with this patch. Is there anything *else* I am missing wrt 16-bit/32-bit data fields that we need to know ? > Testing proves that kernel can correctly receive MSI-X interrupts from > PCIe cards which supports both MSI and MSI-X interrupts. I don't understand what you want to convey with this commit log. To me, the whole comment does not add anything (if I understood it), please let me know what you want to express with it. To me this patch enables MSI-X support because the HW can support them, that's it. Lorenzo > Signed-off-by: Pali Rohár <pali@xxxxxxxxxx> > Reviewed-by: Marek Behún <kabel@xxxxxxxxxx> > Signed-off-by: Marek Behún <kabel@xxxxxxxxxx> > --- > 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 b703b271c6b1..337b61508799 100644 > --- a/drivers/pci/controller/pci-aardvark.c > +++ b/drivers/pci/controller/pci-aardvark.c > @@ -1274,7 +1274,7 @@ static int advk_pcie_init_msi_irq_domain(struct advk_pcie *pcie) > > msi_di = &pcie->msi_domain_info; > msi_di->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; > msi_di->chip = msi_ic; > > pcie->msi_inner_domain = > -- > 2.32.0 >
