Re: [PATCH 0/2] PCI: fix pci-mvebu after conversion to common bridge emul code

[Leigh Brown <leigh@solinno.co.uk>]

On 2019-02-21 23:23, Bjorn Helgaas wrote:
> On Wed, Feb 20, 2019 at 10:48:39AM +0100, Thomas Petazzoni wrote:
>> Hello,
>> 
>> This set of two patches aim at fixing some regression reported by two
>> users (Luis and Leigh), that were introduced by the conversion of the
>> pci-mvebu driver to the common PCI bridge emulation code shared
>> between pci-aardvark and pci-mvebu.
>> 
>> Due to this conversion, some registers of the PCI configuration that
>> used to be read-only are now read-write, making the Linux PCI core
>> believe that some features are implemented by the PCI bridge. Namely
>> in the case of pci-mvebu, the prefetchable memory base/limit registers
>> were read-only, while they are now read-write. Due to this, the Linux
>> PCI core now believes it can configure a prefetchable memory area, but
>> this is not supported by pci-mvebu, which does not have the logic to
>> create the appropriate MBUs windows.
>> 
>> This set of two commits allow PCI controller code to tell the PCI
>> bridge emulation logic about their capabilities. Because we envision
>> that other capabilities than prefetchable memory support might need to
>> be communicated from the PCI controller code to the PCI bridge
>> emulation code in the future, we introduce a "flags" argument, even if
>> for now only one flag is supported.
>> 
>> Lorenzo, let me know what you think about this approach. I am open to
>> suggestions if the proposed approach is not satisfying.
>> 
>> Both patches have been confirmed by Luis and Leigh to fix the
>> regression, but I'll let them give a formal Tested-by.
>> 
>> Best regards,
>> 
>> Thomas Petazzoni
>> 
>> Thomas Petazzoni (2):
>>   PCI: pci-bridge-emul: Create per-bridge copy of register behavior
>>   PCI: pci-bridge-emul: Extend pci_bridge_emul_init() with flags
>> 
>>  drivers/pci/controller/pci-aardvark.c |  2 +-
>>  drivers/pci/controller/pci-mvebu.c    |  2 +-
>>  drivers/pci/pci-bridge-emul.c         | 86 
>> ++++++++++++++++++---------
>>  drivers/pci/pci-bridge-emul.h         | 13 +++-
>>  4 files changed, 73 insertions(+), 30 deletions(-)
> 
> Lorenzo, I assume you'll take both of these, so for both patches,
> 
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> 
> Maybe we should add a stable tag (v4.20+)?

That would be great, as it would get that kernel version working again.

Regards,

Leigh.