On Friday 07 January 2022 17:01:55 Bjorn Helgaas wrote: > On Fri, Jan 07, 2022 at 11:13:48PM +0100, Pali Rohár wrote: > > On Friday 07 January 2022 15:32:16 Bjorn Helgaas wrote: > > > On Thu, Nov 25, 2021 at 01:45:55PM +0100, Pali Rohár wrote: > > > > Interrupt support on mvebu emulated bridges is not implemented yet. > > > > > > Is this mvebu-specific, or is aardvar also affected? > > > > This is pci-mvebu.c driver specific, it does not implement emulation of > > neither INTx, nor MSI interrupts for emulated pci bridge (root port). As > > we know this HW does not have compliant pci root port, it needs to be > > emulated in driver, and emulation for interrupts is missing. (it means > > that also AER interrupt is missing). > > > > And pci-aardvark.c driver has same issue and similar patch is required > > for pci-aardvark.c too. Marek should take care of it. But for > > pci-aardvark we already have implementation which emulates INTx > > interrupts and it is waiting for review on the list: > > https://lore.kernel.org/linux-pci/20211208061851.31867-1-kabel@xxxxxxxxxx/ > > > > > > So properly indicate return value to callers that they cannot request > > > > interrupts from emulated bridge. > > > > > > Pet peeve: descriptions that say "do this *properly*". As though the > > > previous authors were just ignorant or intentionally did something > > > *improperly* :) > > > > > > > Signed-off-by: Pali Rohár <pali@xxxxxxxxxx> > > > > Cc: stable@xxxxxxxxxxxxxxx > > > > --- > > > > drivers/pci/controller/pci-mvebu.c | 10 ++++++++++ > > > > 1 file changed, 10 insertions(+) > > > > > > > > diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c > > > > index 19c6ee298442..a3df352d440e 100644 > > > > --- a/drivers/pci/controller/pci-mvebu.c > > > > +++ b/drivers/pci/controller/pci-mvebu.c > > > > @@ -705,6 +705,15 @@ static struct pci_ops mvebu_pcie_ops = { > > > > .write = mvebu_pcie_wr_conf, > > > > }; > > > > > > > > +static int mvebu_pcie_map_irq(const struct pci_dev *dev, u8 slot, u8 pin) > > > > +{ > > > > + /* Interrupt support on mvebu emulated bridges is not implemented yet */ > > > > + if (dev->bus->number == 0) > > > > + return 0; /* Proper return code 0 == NO_IRQ */ > > > > + > > > > + return of_irq_parse_and_map_pci(dev, slot, pin); > > > > > > Is this something that could be done with a .read_base() op, e.g., > > > make PCI_INTERRUPT_PIN contain zero (PCI_INTERRUPT_UNKNOWN)? > > > > I'm not sure... maybe. I choose this style as after I implement > > emulation of INTx interrupts it allows me just to replace "return 0;" by > > "return my_mapping_function_for_root_port(...);". > > OK, so even after you implement INTx for the emulated Root Ports, the > default of_irq_parse_and_map_pci() is insufficient, and you will > require an mvebu .map_irq() function. That's reasonable. > > "PCI_INTERRUPT_PIN == 0" is the way software learns that a device > doesn't use INTx, of course, and I suppose PCI_INTERRUPT_PIN already > reads as zero, since mvebu_pci_bridge_emul_init() doesn't set > bridge->conf.intpin, and I assume the default value would be zero? > > Bjorn Yes, looks like that zeros are in emulated config space for fields not explicitly initialized. Which is the pci-mvebu.c case. But now I'm looking at pci-aardvark.c driver and it sets PCI_INTERRUPT_PIN register to A: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/pci-aardvark.c?h=v5.16-rc8#n953 And that comment "/* Support interrupt A for MSI feature */" must be total nonsense as INTA for sure is not required for MSI... Plus we know that pci-aardvark.c driver does not implement for pci bridge neither INTx nor MSI... Ach... seems that this code is here since beginning and needs to be fixed...
