Hello, Hot adding a pci device results in improper MPS settings detected, reading 128 even though the upstream port is 256. This causes a warning print to be logged suggesting I should report a bug. :) Here's the dmesg of the hot plug event: [ 2105.051941] pciehp 0000:05:07.0:pcie24: Card present on Slot(27) [ 2107.012811] pci 0000:09:00.0: [8086:0953] type 00 class 0x010802 [ 2107.012838] pci 0000:09:00.0: reg 0x10: [mem 0x00000000-0x00003fff 64bit] [ 2107.012873] pci 0000:09:00.0: reg 0x30: [mem 0x00000000-0x0000ffff pref] [ 2107.014986] pcieport 0000:05:07.0: bridge window [io 0x1000-0x0fff] to [bus 09] add_size 1000 [ 2107.014996] pcieport 0000:05:07.0: res[13]=[io 0x1000-0x0fff] get_res_add_size add_size 1000 [ 2107.015001] pcieport 0000:05:07.0: BAR 13: can't assign io (size 0x1000) [ 2107.015006] pcieport 0000:05:07.0: BAR 13: can't assign io (size 0x1000) [ 2107.015013] pci 0000:09:00.0: BAR 6: assigned [mem 0xd5200000-0xd520ffff pref] [ 2107.015018] pci 0000:09:00.0: BAR 0: assigned [mem 0xdb600000-0xdb603fff 64bit] [ 2107.015030] pcieport 0000:05:07.0: PCI bridge to [bus 09] [ 2107.015037] pcieport 0000:05:07.0: bridge window [mem 0xdb600000-0xdb7fffff] [ 2107.015042] pcieport 0000:05:07.0: bridge window [mem 0xd5200000-0xd52fffff 64bit pref] [ 2107.015060] pci 0000:09:00.0: Max Payload Size 128, but upstream 0000:05:07.0 set to 256; if necessary, use "pci=pcie_bus_safe" and report a bug [ 2107.015079] pci 0000:09:00.0: no hotplug settings from platform The commit message that added the warning indicates it may be a BIOS issue that incorrectly configures this, but BIOS isn't involved with setting the MPS on a device hot add, am I right? Or is that wrong? This is a Dell R620 server, if that matters, though we see this on other platforms as well. Using pci=pcie_bus_perf works around the issue, but that seems a bit odd to suggest to users. Is setting MPS on hot-add something the PCI driver layer ought to be doing, or should I be looking into the platform BIOS instead? Thanks! Keith -- 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
