Am Mittwoch, den 06.03.2019, 09:53 +0000 schrieb Gustavo Pimentel: > 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. At least this behavior was confirmed by Joao Pinto at Synopsys last time the issue was discussed. http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/499591.html Regards, Lucas
