Hi Tim, Am Mittwoch, den 10.05.2017, 14:44 -0700 schrieb Tim Harvey: > On Thu, Apr 27, 2017 at 8:32 AM, Tim Harvey <tharvey@xxxxxxxxxxxxx> wrote: > > On Thu, Apr 27, 2017 at 1:43 AM, Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote: > >> Am Mittwoch, den 26.04.2017, 14:11 -0700 schrieb Tim Harvey: > >>> On Wed, Apr 26, 2017 at 11:15 AM, Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote: > >>> > The DWC host does not support legacy PCI IRQs and MSIs at the same time, > >>> > so we need to fall back to using only legacy IRQs if there is a chance > >>> > that multiple devices with differing MSI capabilities are connected to > >>> > the host. The only configuration where MSIs can be safely used is when > >>> > the device below the host bridge is not a bridge, i.e. the only device > >>> > connected to this host. > >>> > > >>> > By disallowing MSI allocation when multiple devices might be attached > >>> > we get those configurations in a working state. The only configurations > >>> > that depend on MSIs being available, that I am aware of, are some > >>> > embedded devices with a PCIe attached FPGA, that is incapable of > >>> > generating PCI legacy IRQs. Those are kept working by allowing MSIs > >>> > when only a single device is attached to the host. > >>> > > >>> > Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx> > >>> > --- [...] > Lucas, > > Are you not able to repeat my findings? Yes, I see what's going on. > Since Linux 4.8 IMX PCIe is completely broken for PCIe devices that do > not support MSI interrupts (and there are a whole lot of 802.11n > radios that fall into this category) as you can no longer disable MSI > because the IMX PCIe driver depends on it. > > It seems like your patch is the right approach but something must > still be getting set that causes the legacy interrupts to not fire. The issue here are the port-services, which are using MSI when available, which might conflict with the device requirements, even if only a single device is attached. Probably we need to disable MSI on all systems, unless we know that we absolutely need them (EP devices, which don't support legacy IRQs). I'll send a patch to do this, but other issues have been higher priority again. Regards, Lucas
