Hi Frank, Am Donnerstag, den 10.09.2015, 13:37 -0400 schrieb Frank Jenner: > Hi Lucas, > > Thanks for the quick response. See inline: > > On Thu, Sep 10, 2015 at 9:57 AM, Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote: [...] > > > > An implementation for the i.MX6 is already sitting in Bjorns PCI > > maintainer tree and is expected to be merged in kernel 4.4. > > > > I took a look at Bjorn's pci-4.4/host-designware branch and saw your > commits. It looks like the patches I'm using apply most of the same > changes. While they do enable me to get multiple MSIs back from > pci_enable_msi_range() and I get the correct IRQs back to my ISR, I > still run into the issue below when attempting to get the full 32 > vectors. > > >> Unfortunately, even if I work around the arch_setup_msi_irqs() limitation > >> (which I've done by trying out patches 448141 and 448142 from > >> http://patchwork.ozlabs.org/project/linux-pci/list/) and break through to > >> the assign_irq() function in drivers/pci/host/pcie-designware.c, I still > >> cannot allocate all 32 MSIs that my device reports. > >> > >> It appears that one of the bits in the msi_irq_in_use bitmap is already set > >> prior to my driver requesting any MSIs, meaning there aren't enough free > >> slots for the 32 MSIs I am requesting, and causing the function to fail with > >> -ENOSPC. Based on the output from /proc/interrupts, I believe that the PCIe > >> PME service driver is consuming one of the 32 available MSI slots. Thus, my > >> second question is: > >> > >> 2.) Is it possible to leverage all 32 MSIs while still using PCIe PME? > >> > >> I tried using the kernel command line argument pcie_pme=nomsi, but that > >> appeared to disable all MSIs for the device rather than just making the PME > >> service driver use some other mechanism. > >> > > It should be possible to make PME use a legacy INT, but I would have to > > look this up in the code. > > Could you please elaborate on this? I'm a little confused why PME > occupies one of the MSI slots in the first place. Also, as I thought a > device could only use either MSIs or legacy INTs (but not both), is it > even possible for PME to use legacy INTs while my driver uses MSIs? > > Sorry, I'm not sure about this myself. > > Another alternative is to extend the i.MX6 driver. It should be able to > > provide up to 256 MSI interrupt vectors. But I have no way to test that, > > so if you could help with testing I can certainly come up with a patch > > for that. > > Where does the 256 come from? > It's the size of the register space available for MSI IRQs in the i.MX6 implementation. > I appreciate the help, and I would be happy to test out a patch for > you with the caveat that I'm using a custom board so I can only test > any changes against our specific device. > That's totally fine. I can test that I don't break the currently working cases myself, so I only need you to test if the extension works as I have no EP with such a large number of MSI IRQs. Regards, Lucas -- Pengutronix e.K. | Lucas Stach | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
