Hi, On 04/03/2019 20:18, Marc Zyngier wrote: > Hi both, > > On Mon, 04 Mar 2019 19:39:45 +0000, > Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote: >> (snipped) >>>> >>>> As MSI and legacy IRQs are already mutually exclusive on the DWC core, >>>> as the core won't forward any legacy IRQs once any MSI has been enabled, >>>> users wishing to use legacy IRQs already need to explictly disable MSI >>>> support (usually via the pci=nomsi kernel commandline option). To avoid >>>> any issues with MSI conflicting with legacy IRQs, just skip all of the >>>> DWC MSI initalization, including the IRQ line claim, when MSI is disabled. >>> >>> Does this mean that if we have a device that uses legacy IRQs, the >>> user has to figure out to boot with "pci=nomsi"? >> >> As long as there is only a single device connected and there are no >> port services things will work. If port services are active, those will >> start to use MSIs, breaking legacy IRQs in the process. >> >> I've asked Synopsys if there is a workaround for this, but it seems >> that the core is working "as designed" with no workaround for this icky >> behavior. > > Is this the general DWC controller behaviour? Or something that is > specific to a given implementation? I can't believe someone actually > thought this is an acceptable behaviour... > > Gustavo, can you please check with your HW colleagues and let > everybody know what's the official Synopsys position on this? > Sure, I can ask the HW team to provide me more info about this, This can take a while. Unfortunately on my setup I only have MSI and MSI-X, therefore I can't really test what has been statemented. Regards, Gustavo
