On 2014/7/4 14:26, Brian Becker wrote: > I am booting a kernel with CONFIG_ACPI=n on a platform which does not > support ACPI. Hmmm, so my suggestion is 1. Add quirk to detect 430FX chipset, if detected, disable MSI in this platform. or 2. Append boot argument pci=nomsi in OS command line when the OS running on your old platform. Maybe other guys has some advices. :) > > On Fri, Jul 4, 2014 at 1:59 AM, Yijing Wang <wangyijing@xxxxxxxxxx> wrote: >>>>> There is a NVIDIA G96 GPU (which is PCIe only) hanging off of a PCIe >>>>> <-> PCI bridge (all on one card), which is plugged into a motherboard >>>>> with the 430FX chipset (PCI 2.0 supported). >>>>> >>>>> The GPU PCI device, of course, has full support for MSI. However my >>>>> understanding is that MSI won't actually work here. This is confirmed >>>>> by the fact that if we let nouveau enable MSI, the device doesn't work >>>>> (presumably due to lack of interrupt delivery, although I admit to not >>>>> having debugged it that far). How do I, as a nouveau driver developer, >>>>> know not to call pci_enable_msi? Or alternatively how can >>>>> pci_enable_msi be taught not to succeed in this case? >>>> >>>> You can set bus_flags or global pci_msi_enable flag by add quirk function. >>>> You can refer to examples in drivers/pci/quirk.c >>>> >>>> Linux support some broken chipsets or devices to disable msi during device initialization by add quirk. >>> >>> So let me get this straight -- you're suggesting I add a quirk for >>> every PCI chipset that doesn't support MSI? There are probably >>> hundreds of these... anything made before 1999 or so, and probably a >>> bunch since then too. There _has_ to be a way to do this generically. >>> Is the PCI spec version anywhere in the root hub? >> >> There is no register to identify PCI spec version in PCI config space registers. >> If your platform boot up with ACPI, you can setting ACPI FADT boot flag to disable MSI, >> you can refer to this in ACPI 5.2.9.3 chapter "Fixed ACPI Description Table Boot Architecture Flags" >> >> >>> >>> Perhaps we can check if every bridge on the way to the CPU has the MSI >>> capability (including the root hub)? (And naturally _that_ won't >>> work... on my sandybridge laptop, the host bridge doesn't have the MSI >>> cap but the system most definitely supports MSI.) >>> >>> Adding Bjorn... perhaps you know? Some of the info has been stripped >>> out by now, you can see the full lspci -vvvxxx at >>> http://marc.info/?l=linux-pci&m=140443441730503&w=2 >>> >>> -ilia >>> >>> . >>> >> >> >> -- >> Thanks! >> Yijing >> > > . > -- Thanks! Yijing -- 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
