On Wed, 24 Aug 2016 14:30:00 -0500 Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > On Wed, Aug 24, 2016 at 03:27:23PM +0100, Lorenzo Pieralisi wrote: > > [ +Bjorn, Punit] > > > > On Wed, Aug 24, 2016 at 04:06:13AM -0700, Duc Dang wrote: > > > [Resend in plain text mode] > > > > > > Hi Lorenzo, Rafael, > > > > > > ACPI 6.1 spec does not specify how to set interrupt polarity and > > > trigger mode in _PRT when the interrupts are static (hardwired to > > > specific interrupt inputs in interrupt controller). In current > > > acpi_pci_irq_enable (drivers/acpi/pci_irq.c) implementation, by > > > default the trigger mode is set to LEVEL_SENSITIVE, polarity is set to > > > ACTIVE_LOW. This default setting won't work for ARM64 GICv2, GICv2m, > > > GICv3 controllers and will cause failures in PCIe AER, PME services > > > (on X-Gene platforms). > > PCI (not PCIe) r3.0, sec 2.2.6, says "Interrupts on PCI are optional > and defined as 'level sensitive,' asserted low." > > I've heard before that ARM64 does this differently, but I still don't > understand the difference. Obviously if you plug a legacy PCI card > into an ARM64 system, it's still going to pull INTA# low to assert an > interrupt. So is there something special about ARM64 that inverts > that, or what? There is certainly an inverter somewhere on the interrupt path, because the GIC triggers on level high, not level low. But I don't think that's the issue Duc is trying to outline here, because that's not something SW can fix. I'm worried that in his system, the interrupt is edge triggered instead. > > > > Is there any way to specify polarity and trigger mode for static > > > interrupts in _PRT? > > There is no way I'm aware of in _PRT to specify polarity and trigger > mode. I don't know the history, but my guess is that it would be seen > as superfluous given that the PCI spec requires level, active low. > > Obviously I'm missing something important. Same here, unless the HW is not PCI compliant... Thanks, M. -- Jazz is not dead. It just smells funny. -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
