Dear Marc Zyngier, On Tue, 26 Jan 2016 13:52:25 +0000, Marc Zyngier wrote: > Let's take the (outlandish) example of an interrupt controller > capable of handling both wired interrupts and PCI MSIs. > > With the current code, the PCI MSI domain is going to be tagged > with DOMAIN_BUS_PCI_MSI, and the wired domain with DOMAIN_BUS_ANY. > > Things get hairy when we start looking up the domain for a wired > interrupt (typically when creating it based on some firmware > information - DT or ACPI). > > In irq_create_fwspec_mapping(), we perform the lookup using > DOMAIN_BUS_ANY, which is actually used as a wildcard. This gives > us one chance out of two to end up with the wrong domain, and > we try to configure a wired interrupt with the MSI domain. > Everything grinds to a halt pretty quickly. > > What we really need to do is to start looking for a domain that > would uniquely identify a wired interrupt domain, and only use > DOMAIN_BUS_ANY as a fallback. > > In order to solve this, let's introduce a new DOMAIN_BUS_WIRED > token, which is going to be used exactly as described above. > Of course, this depends on the irqchip to setup the domain > bus_token, and nobody had to implement this so far. > > Only so far. > > Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> Tested-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx> - On Marvell Armada XP, which uses the Marvell MPIC for both wired interrupts and MSI interrupts - On Marvell Armada 38x, which uses the ARM GIC for most wired interrupts and the Marvell MPIC for MSI interrupts With an Intel e1000e PCIe NIC, with both PCI_MSI=y and PCI_MSI disabled cases have been tested. When MSI support is disabled it gracefully falls back to a wired interrupt, as expected. Thanks! Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
