On Thu, May 11, 2017 at 7:08 AM, Tim Harvey <tharvey@xxxxxxxxxxxxx> wrote: > On Thu, May 11, 2017 at 1:16 AM, Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote: >> 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 >> > > Lucas, > > Thanks, this fix is something that's beyond my experience or I would > be glad to do it. The PCIe driver has been changing very rapidly in > recent kernel versions and there is no single patch that can be > reverted to 'fix' this long-standing issue. I'm really surprised > others haven't chimed in with reports of it being broken as its been > an issue since 4.8. > > Is it worth removing the 'depends on PCI_MSI_IRQ_DOMAIN' from > PCIE_DW_HOST and PCI_IMX6 and defaulting MSI off until your proposed > fix is ready and working? That is precisely what I have to do on 4.8+ > kernels to get them working for our IMX6 users using ath9k radios > (making distro's like Ubuntu a problem as they run a fairly standard > 4.8 kernel). > > Tim Lucas, Any cycles to put together another attempt to allow legacy IRQ's on IMX6? Thanks, Tim
