Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH v8 3/6] pci:host: Add Altera PCIe host controller driver | Date | Mon, 12 Oct 2015 14:03:04 +0200 |
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On Friday 09 October 2015 18:15:40 Bjorn Helgaas wrote: > > I don't know if this should be a kernel taint, a simple warning in > dmesg, or what. I guess the tainting mechanism is probably too > general-purpose for this, and add_taint() doesn't give any dmesg > indication. We wouldn't see the taint unless the problem actually > caused an oops or panic. In this case, I think I want a clue in dmesg > so we have a chance of seeing it even if there is no oops. So > probably something like a dev_warn("non-compliant config accesses") > would work. > > You really should double-check with the hardware guys, because it's > pretty obvious that the PCI spec requires 1- and 2-byte config > accesses to work correctly. For example, if you read/modify/write to > update PCI_COMMAND, you will inadvertently clear the RW1C bits in > PCI_STATUS.
Would it help to require a DT property here that flags the device as having a broken config space?
Then we could implement both in the driver, and only use the RMW based implementation if the firmware describes the device as "altera,broken-pci-config-space".
Arnd
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