Revert "PCI: tegra: Do not allocate MSI target memory"
This reverts commit d7bd554f. It turns out that Tegra20 has a bug in the implementation of the MSI target address register (which is worked around by the existence of the struct tegra_pcie_soc.msi_base_shift parameter) that restricts the MSI target memory to the lower 32 bits of physical memory on that particular generation. The offending patch causes a regression on TrimSlice, which is a Tegra20-based device and has a PCI network interface card. An initial, simpler fix was to change the MSI target address for Tegra20 only, but it was pointed out that the offending commit also prevents the use of 32-bit only MSI capable devices, even on later chips. Technically this was never guaranteed to work with the prior code in the first place because the allocated page could have resided beyond the 4 GiB boundary, but it is still possible that this could've introduced a regression. The proper fix that was settled on is to select a fixed address within the lowest 32 bits of physical address space that is otherwise unused, but testing of that patch has provided mixed results that are not fully understood yet. Given all of the above and the relative urgency to get this fixed in v4.13, revert the offending commit until a universal fix is found. Fixes: d7bd554f ("PCI: tegra: Do not allocate MSI target memory") Reported-by: Tomasz Maciej Nowak <tmn505@gmail.com> Reported-by: Erik Faye-Lund <kusmabite@gmail.com> Signed-off-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: stable@vger.kernel.org # 4.13.x
Showing
Please register or sign in to comment